SSC CGL Previous Year Questions (2023-20): Physics | SSC CGL General Awareness Previous Year Papers (Topic-wise) PDF Download

 Page 1


 Pinnacle  Physics 
 Physics 
 Light and Optics 
 Q.1.  A  concave  spherical  mirror  has  a 
 radius  of  curvature  of  30  cm.  An  object 
 was  placed  15  cm  away  from  the  pole  in 
 front  of  the  mirror  on  the  principal  axis. 
 Choose  the  correct  option  for  the 
 position,  size  and  nature  of  the  image 
 formed, respectively. 
 SSC Stenographer 13/10/2023 (Morning) 
 (a) Behind the mirror, enlarged, virtual 
 and erect 
 (b) At in?nity, highly enlarged, real and 
 inverted 
 (c) Between Focus and Centre, 
 diminished, real and inverted 
 (d) At the focus, highly diminished 
 point-sized, real and inverted 
 Sol.1.(b)  At  In?nity,  highly  enlarged,  real 
 and  inverted.  We  know  that,  focus  of  a 
 mirror,  f  =  R/2,  where  R  is  the  radius  of 
 curvature  of  the  mirror.  Here  in  this  case, 
 f  =  -  30/2  =  -15  cm.  Also,  distance  of  the 
 object  from  the  mirror,  u  =  -15  cm.  It 
 means  that  the  object  is  placed  at  the 
 focus  of  the  mirror.  Now  it  is  clear  that 
 when  the  object  is  placed  at  focus  of  the 
 mirror,  the  respective  image  will  be 
 formed  at  in?nity.  The  size  of  the  image 
 would  be  highly  enlarged.  The  nature  of 
 the image would be real and inverted. 
 Q.2.  In  optics,  which  term  refers  to  the 
 opening  of  the  diaphragm  of  a  lens  that 
 spatially limits the propagation of light ? 
 SSC MTS 13/09/2023 (1st Shift) 
 (a) Collimator  (b) Aperture 
 (c) Apostilb  (d) Meniscus 
 Sol.2.(b)  Aperture.  Collimator  -  A  device 
 which  narrows  a  beam  of  particles  or 
 waves.  Apostilb  -  An  obsolete  unit  of 
 luminance.  Meniscus  -  A  C-shaped  piece 
 of  tough,  rubbery  cartilage  that  acts  as  a 
 shock  absorber  between  the  shinbone 
 and the thigh bone. 
 Q.3.  White light is an example of: 
 SSC CHSL 04/08/2023 (2nd shift) 
 (a) laser light 
 (b) plane polarized light 
 (c) monochromatic light 
 (d) polychromatic light 
 Sol.3.(d)  Polychromatic  light  -  The  light 
 consists  of  a  broad  range  of 
 wavelengths.  Examples  -  Mercury  Light, 
 Sunlight,  laser-pumped  plasma  light. 
 Monochromatic  light  -  The  light  consists 
 of  only  one  speci?c  wavelength. 
 Examples  -  laser  beam,  Sodium  lamps, 
 Spark  lamps.  Plane  polarized  light  -  It 
 consists  of  waves  in  which  the  direction 
 of  vibration  is  the  same  for  all  waves. 
 Examples  -  laser  lights  and  devices. 
 Laser  light  -  Laser  (Light  Ampli?cation  by 
 Stimulated  Emission  of  Radiation)  is  an 
 arti?cial  source  of  light  radiation  that 
 emits  a  coherent  beam  of  photons,  as 
 the  source  is  stable  in  frequency, 
 wavelength, and power. 
 Q.4.  Which  telescope  was  invented  by 
 Isaac  Newton  in  the  17th  century  by 
 using  a  concave  mirror  to  collect  light 
 instead  of  a  simple  lens  which  produces 
 false  colors  due  to  the  dispersion  of 
 light? 
 SSC CHSL 09/08/2023 (3rd shift) 
 (a) Re?ecting telescope 
 (b) Infrared telescope 
 (c) Monocular telescope 
 (d) Graphic telescope 
 Sol.4.(a)  Re?ecting  telescope  -  Uses 
 mirrors  which  cause  light  to  re?ect  at 
 different  angles  within  the  optical  tube 
 and  extends  the  overall  light  path.  Two 
 major  types  of  telescopes  :  Re?ecting 
 Telescopes  and  Refracting  Telescopes 
 (used  lenses  to  magnify  objects). 
 Infrared  telescope  :  Uses  infrared  light  to 
 detect celestial bodies. 
 Q.5.  The  minimum  distance  of  distinct 
 vision  for  a  young  adult  person  with  no 
 defect in eyes is: 
 SSC CHSL 11/08/2023 (4th shift) 
 (a) 20 m  (b) 25 cm  (c) 20 cm  (d) 25 m 
 Sol.5.(b)  25  cm.  For  a  normal  eye,  the  far 
 point  is  at  in?nity  and  the  near  point  of 
 distinct  vision  is  about  25  cm  in  front  of 
 the  eye.  Hypermetropia  (far-sightedness) 
 :  When  the  point  goes  farther  from  25 
 cm.  Lens  used  :  Convex.  Myopia 
 (Nearsightedness):  Near  objects  appear 
 clear,  but  objects  farther  away  look 
 blurry. Lens used: Concave. 
 Q.6.  Which  colour  of  light  from  VIBGYOR 
 has minimum energy ? 
 SSC CHSL 14/08/2023 (1st shift) 
 (a) Green (b) Violet (c) Yellow (d) Red 
 Sol.6.(d)  Red  .  It  has  the  longest 
 wavelength  and  least  energy  of  the 
 visible  colors  of  light.  Wavelength  -  The 
 distance  between  two  successive  crests 
 or  troughs.  Violet  has  the  shortest 
 wavelength.  Frequency  -  It  refers  to  the 
 number  of  waves  passing  through  a 
 point  per  second.  Violet  has  the  highest 
 frequency.  The  white  light  consists  of  7 
 colors  VIBGYOR  (Violet  -  Indigo  -  Blue  - 
 Green - Yellow - Orange - Red). 
 Q.7.  Why  can  you  not  see  objects  in  a 
 dim  lit  room  when  you  come  from  a 
 brightly lit room? 
 SSC CGL 25/07/2023 (4th shift) 
 (a) The iris dilates the eye lens to allow 
 less light to enter the eye. 
 (b) The iris contracts the pupil to allow 
 less light to enter the eye. 
 (c) The vitreous humour dilates the pupil 
 to allow less light to enter the eye. 
 (d) The cornea contracts the pupil to 
 allow less light to enter the eye. 
 Sol.7.(b)  Iris  -  It  gives  a  distinct  color  to 
 the  eyes.  The  eyeball  is  spherical  in 
 shape  having  a  diameter  of  23  mm. 
 Vitreous  humor  present  in  between  lens 
 and  retina.  Retina  contains  three  layers 
 of  neural  cells  (ganglion  cells,  bipolar 
 cells,  photoreceptor  cells).  Cornea  -  The 
 front  most  and  transparent  covering  of 
 the  eye.  Light  enters  the  human  eye 
 through the cornea. 
 Q.8.  What  will  be  the  focal  length  of  a 
 convex  lens  with  the  power  of  a  +2.5 
 Diopter? 
 Higher Secondary 28/06/2023 ( Shift - 2) 
 (a) 20 cm (b) 10 cm (c) 40 cm (d) 5 cm 
 Sol.8.(c) 40 cm.  Using the formula: 
 focal  length  (f)  of  convex  Lens  =  1/Power 
 (P) 
 Given,  the power (P) =  +2.5 diopters 
 then  focal  length:  f  =  1  /  2.5  =  0.4  meters 
 =  40  centimeters  .  Focal  length  of  convex 
 lens  is  always  positive  and  concave  lens 
 is always negative. 
 Q.9.  Raman  wants  to  use  a  rear-view 
 mirror  in  his  vehicle.  Which  type  of 
 mirror should he pick for it ? 
 SSC CHSL 10/03/2023 (2nd Shift) 
 (a) Convex Mirrors       (b) Plane Mirrors 
 (c) Cylindrical Mirrors  (d) Concave Mirrors 
 Sol.9.(a)  Convex  Mirrors.  This  is 
 because  they  give  an  erect,  virtual,  full 
 size  diminished  image  of  distant  objects 
 with  a  wider  ?eld  of  view.  Uses  - 
 Sunglasses, street lights. 
 Q.10.  An  image  formed  by  the  convex 
 mirror is always _________. 
 SSC CHSL 14/03/2023 (3rd Shift) 
 (a) virtual and inverted (b) real and erect 
 (c) virtual and erect      (d) real and inverted 
 Sol.10.(c)  Virtual  and  erect.  Convex 
 mirror  (Diverging  Mirror)  -  It  has  a 
 re?ecting  surface  that  bulges  outwards, 
 and  away  from  the  centre  of  curvature. 
 Uses  -  Rear  view  mirrors,  Street  light 
 re?ector, etc. 
 Q.11.  Which of the following statements 
 www.ssccglpinnacle.com                                                 Download Pinnacle Exam Preparation App 410
Page 2


 Pinnacle  Physics 
 Physics 
 Light and Optics 
 Q.1.  A  concave  spherical  mirror  has  a 
 radius  of  curvature  of  30  cm.  An  object 
 was  placed  15  cm  away  from  the  pole  in 
 front  of  the  mirror  on  the  principal  axis. 
 Choose  the  correct  option  for  the 
 position,  size  and  nature  of  the  image 
 formed, respectively. 
 SSC Stenographer 13/10/2023 (Morning) 
 (a) Behind the mirror, enlarged, virtual 
 and erect 
 (b) At in?nity, highly enlarged, real and 
 inverted 
 (c) Between Focus and Centre, 
 diminished, real and inverted 
 (d) At the focus, highly diminished 
 point-sized, real and inverted 
 Sol.1.(b)  At  In?nity,  highly  enlarged,  real 
 and  inverted.  We  know  that,  focus  of  a 
 mirror,  f  =  R/2,  where  R  is  the  radius  of 
 curvature  of  the  mirror.  Here  in  this  case, 
 f  =  -  30/2  =  -15  cm.  Also,  distance  of  the 
 object  from  the  mirror,  u  =  -15  cm.  It 
 means  that  the  object  is  placed  at  the 
 focus  of  the  mirror.  Now  it  is  clear  that 
 when  the  object  is  placed  at  focus  of  the 
 mirror,  the  respective  image  will  be 
 formed  at  in?nity.  The  size  of  the  image 
 would  be  highly  enlarged.  The  nature  of 
 the image would be real and inverted. 
 Q.2.  In  optics,  which  term  refers  to  the 
 opening  of  the  diaphragm  of  a  lens  that 
 spatially limits the propagation of light ? 
 SSC MTS 13/09/2023 (1st Shift) 
 (a) Collimator  (b) Aperture 
 (c) Apostilb  (d) Meniscus 
 Sol.2.(b)  Aperture.  Collimator  -  A  device 
 which  narrows  a  beam  of  particles  or 
 waves.  Apostilb  -  An  obsolete  unit  of 
 luminance.  Meniscus  -  A  C-shaped  piece 
 of  tough,  rubbery  cartilage  that  acts  as  a 
 shock  absorber  between  the  shinbone 
 and the thigh bone. 
 Q.3.  White light is an example of: 
 SSC CHSL 04/08/2023 (2nd shift) 
 (a) laser light 
 (b) plane polarized light 
 (c) monochromatic light 
 (d) polychromatic light 
 Sol.3.(d)  Polychromatic  light  -  The  light 
 consists  of  a  broad  range  of 
 wavelengths.  Examples  -  Mercury  Light, 
 Sunlight,  laser-pumped  plasma  light. 
 Monochromatic  light  -  The  light  consists 
 of  only  one  speci?c  wavelength. 
 Examples  -  laser  beam,  Sodium  lamps, 
 Spark  lamps.  Plane  polarized  light  -  It 
 consists  of  waves  in  which  the  direction 
 of  vibration  is  the  same  for  all  waves. 
 Examples  -  laser  lights  and  devices. 
 Laser  light  -  Laser  (Light  Ampli?cation  by 
 Stimulated  Emission  of  Radiation)  is  an 
 arti?cial  source  of  light  radiation  that 
 emits  a  coherent  beam  of  photons,  as 
 the  source  is  stable  in  frequency, 
 wavelength, and power. 
 Q.4.  Which  telescope  was  invented  by 
 Isaac  Newton  in  the  17th  century  by 
 using  a  concave  mirror  to  collect  light 
 instead  of  a  simple  lens  which  produces 
 false  colors  due  to  the  dispersion  of 
 light? 
 SSC CHSL 09/08/2023 (3rd shift) 
 (a) Re?ecting telescope 
 (b) Infrared telescope 
 (c) Monocular telescope 
 (d) Graphic telescope 
 Sol.4.(a)  Re?ecting  telescope  -  Uses 
 mirrors  which  cause  light  to  re?ect  at 
 different  angles  within  the  optical  tube 
 and  extends  the  overall  light  path.  Two 
 major  types  of  telescopes  :  Re?ecting 
 Telescopes  and  Refracting  Telescopes 
 (used  lenses  to  magnify  objects). 
 Infrared  telescope  :  Uses  infrared  light  to 
 detect celestial bodies. 
 Q.5.  The  minimum  distance  of  distinct 
 vision  for  a  young  adult  person  with  no 
 defect in eyes is: 
 SSC CHSL 11/08/2023 (4th shift) 
 (a) 20 m  (b) 25 cm  (c) 20 cm  (d) 25 m 
 Sol.5.(b)  25  cm.  For  a  normal  eye,  the  far 
 point  is  at  in?nity  and  the  near  point  of 
 distinct  vision  is  about  25  cm  in  front  of 
 the  eye.  Hypermetropia  (far-sightedness) 
 :  When  the  point  goes  farther  from  25 
 cm.  Lens  used  :  Convex.  Myopia 
 (Nearsightedness):  Near  objects  appear 
 clear,  but  objects  farther  away  look 
 blurry. Lens used: Concave. 
 Q.6.  Which  colour  of  light  from  VIBGYOR 
 has minimum energy ? 
 SSC CHSL 14/08/2023 (1st shift) 
 (a) Green (b) Violet (c) Yellow (d) Red 
 Sol.6.(d)  Red  .  It  has  the  longest 
 wavelength  and  least  energy  of  the 
 visible  colors  of  light.  Wavelength  -  The 
 distance  between  two  successive  crests 
 or  troughs.  Violet  has  the  shortest 
 wavelength.  Frequency  -  It  refers  to  the 
 number  of  waves  passing  through  a 
 point  per  second.  Violet  has  the  highest 
 frequency.  The  white  light  consists  of  7 
 colors  VIBGYOR  (Violet  -  Indigo  -  Blue  - 
 Green - Yellow - Orange - Red). 
 Q.7.  Why  can  you  not  see  objects  in  a 
 dim  lit  room  when  you  come  from  a 
 brightly lit room? 
 SSC CGL 25/07/2023 (4th shift) 
 (a) The iris dilates the eye lens to allow 
 less light to enter the eye. 
 (b) The iris contracts the pupil to allow 
 less light to enter the eye. 
 (c) The vitreous humour dilates the pupil 
 to allow less light to enter the eye. 
 (d) The cornea contracts the pupil to 
 allow less light to enter the eye. 
 Sol.7.(b)  Iris  -  It  gives  a  distinct  color  to 
 the  eyes.  The  eyeball  is  spherical  in 
 shape  having  a  diameter  of  23  mm. 
 Vitreous  humor  present  in  between  lens 
 and  retina.  Retina  contains  three  layers 
 of  neural  cells  (ganglion  cells,  bipolar 
 cells,  photoreceptor  cells).  Cornea  -  The 
 front  most  and  transparent  covering  of 
 the  eye.  Light  enters  the  human  eye 
 through the cornea. 
 Q.8.  What  will  be  the  focal  length  of  a 
 convex  lens  with  the  power  of  a  +2.5 
 Diopter? 
 Higher Secondary 28/06/2023 ( Shift - 2) 
 (a) 20 cm (b) 10 cm (c) 40 cm (d) 5 cm 
 Sol.8.(c) 40 cm.  Using the formula: 
 focal  length  (f)  of  convex  Lens  =  1/Power 
 (P) 
 Given,  the power (P) =  +2.5 diopters 
 then  focal  length:  f  =  1  /  2.5  =  0.4  meters 
 =  40  centimeters  .  Focal  length  of  convex 
 lens  is  always  positive  and  concave  lens 
 is always negative. 
 Q.9.  Raman  wants  to  use  a  rear-view 
 mirror  in  his  vehicle.  Which  type  of 
 mirror should he pick for it ? 
 SSC CHSL 10/03/2023 (2nd Shift) 
 (a) Convex Mirrors       (b) Plane Mirrors 
 (c) Cylindrical Mirrors  (d) Concave Mirrors 
 Sol.9.(a)  Convex  Mirrors.  This  is 
 because  they  give  an  erect,  virtual,  full 
 size  diminished  image  of  distant  objects 
 with  a  wider  ?eld  of  view.  Uses  - 
 Sunglasses, street lights. 
 Q.10.  An  image  formed  by  the  convex 
 mirror is always _________. 
 SSC CHSL 14/03/2023 (3rd Shift) 
 (a) virtual and inverted (b) real and erect 
 (c) virtual and erect      (d) real and inverted 
 Sol.10.(c)  Virtual  and  erect.  Convex 
 mirror  (Diverging  Mirror)  -  It  has  a 
 re?ecting  surface  that  bulges  outwards, 
 and  away  from  the  centre  of  curvature. 
 Uses  -  Rear  view  mirrors,  Street  light 
 re?ector, etc. 
 Q.11.  Which of the following statements 
 www.ssccglpinnacle.com                                                 Download Pinnacle Exam Preparation App 410
 Pinnacle  Physics 
 regarding the lenses is/are correct? 
 I. Power of a convex lens is represented 
 as a positive number. 
 II. Power of a concave lens is 
 represented as a negative number. 
 SSC CHSL 17/03/2023 (4th Shift) 
 (a) Both I and II  (b) Only II 
 (c) Only I  (d) Neither I nor II 
 Sol.11.(a)  Both  I  and  II.  The  focal  length  of 
 the  convex  lens  is  always  positive.  The 
 power  of  the  lens  = 
 .  If  the  focal  length 
 1 
 ??????????     ??????????h ( ????     ?????????? )
 is  positive,  then  power  is  always  positive. 
 Uses  of  convex  lens  -  Magnifying  glasses, 
 Eyeglasses, Cameras, Microscopes etc. 
 A  concave  lens  (diverging  lens)  diverges 
 the  rays  incident  on  it.  Its  power  is 
 negative.  Uses  of  concave  lenses  - 
 telescopes, lasers etc. 
 Q.12.  Which  of  the  following  pair  of 
 position  of  object  –  position  of  image  – 
 size  of  image,  is  NOT  correct  for  concave 
 mirror? 
 SSC CPO 10/11/2022 (Morning) 
 (a) At F - At in?nity - Highly enlarged 
 (b) Between C and F - Beyond C - 
 Enlarged 
 (c) Beyond C - Between F and C - 
 Diminished 
 (d) At in?nity - At C - Highly diminished 
 Sol.12.(d)  At  in?nity  -  At  C  -  Highly 
 diminished.  Spherical  mirrors  are  of  two 
 types,  concave  and  convex.  Image 
 formation  by  Concave  Mirror  (Object 
 Position  -  Image  Position  -  Image  Nature 
 and  Size)  :  (At  In?nity  -  At  F  -  Real,  point 
 size);  (Beyond  Center  C  -  Between  C  and 
 F  (Focus)  -  Diminished,  Real  and 
 Inverted);  (On  Centre  -  Real,  inverted,  and 
 same  size);  (Between  Centre  (C)  and 
 Focus  (F)  -  Beyond  Centre  -  Real, 
 inverted,  and  larger);  (on  Focus  -  In?nity  - 
 Real,  inverted,  and  enlarged);  (On  Focal 
 length  (Between  Pole  and  Focus)  - 
 Behind  Mirror  -  Virtual,  straight  and 
 enlarged). 
 Q.13.  If  ‘u’  is  the  object-distance,  ‘v’  is  the 
 image-distance  and  ‘f’  is  the  focal  length 
 of  a  spherical  mirror  then  which  of  the 
 following  is  a  correct  expression  for  the 
 mirror formula? 
 SSC MTS 07/07/2022 (Morning) 
 (a) 1/v + 1/u = –1/f    (b) 1/v – 1/u = 1/f 
 (c) 1/v + 1/u = 1/f       (d) 1/v – 1/u = –1/f 
 Sol.13.(c)  1/v  +  1/u  =  1/f  .  There  are  two 
 types  of  spherical  mirrors  :  concave 
 mirrors  (If  the  re?ective  surface  is  on  the 
 side  curved  inwards)  and  convex  mirrors 
 (if the re?ective surface is curved 
 outwards). The  lens formula  is 1/v-1/u 
 = 1/f. 
 Q.14.  The  splitting  of  white  light  into  its 
 component colours is called ______. 
 SSC MTS 12/07/2022 (Morning) 
 (a) refraction  (b) re?ection 
 (c) scattering  (d) dispersion 
 Sol.14.(d)  Dispersion  .  Refraction  - 
 Redirection  of  a  wave  as  it  passes  from 
 one  medium  to  another.  Re?ection  - 
 When  a  ray  of  light  approaches  a  smooth 
 polished surface, it bounces back. 
 Q.15.  The  re?ection  on  a  bathroom 
 mirror,  the  lake,  and  the  glare  on  a  pair  of 
 glasses  are  caused  by  which  type  of 
 re?ection? 
 SSC CHSL 03/06/2022 (Evening) 
 (a) Multiple re?ection 
 (b) Specular re?ection 
 (c) Glossy re?ection 
 (d) Diffused re?ection 
 Sol.15.(b)  Specular  re?ection  is  de?ned 
 as  light  re?ected  from  a  smooth  surface 
 at  a  de?nite  angle  like  a  re?ection  on  a 
 bathroom  mirror.  Diffuse  re?ection  is 
 produced  by  rough  surfaces  that  tend  to 
 re?ect  light  in  all  directions  like  reading  a 
 newspaper.  Multiple  re?ections,  when 
 we  take  two  mirrors,  a  single  source  of 
 light  can  be  re?ected  multiple  times  like 
 in  a  barber's  shop,  we  see  the  back  of  the 
 head  using  multiple  re?ections  of  two 
 mirrors. 
 Q.16.  Which  of  the  following  elements  is 
 NOT  suitable  for  the  fabrication  of  a  light 
 emitting diode structure? 
 SSC CGL 12/04/2022 (Afternoon) 
 (a) Gallium phosphide 
 (b) Indium gallium nitride 
 (c) Germanium 
 (d) Gallium arsenide 
 Sol.16.(c)  Germanium  (Group  14,  Atomic 
 number  32)  -  It  is  a  semiconductor 
 (properties  between  the  metals  and  the 
 non-metals).  Uses  -  as  a  transistor,  used 
 in  wide-angle  camera  lenses  and 
 objective lenses for microscopes. 
 Q.17  .  Gold  and  copper  happen  to  absorb 
 ______and violet light, leaving yellow light. 
 SSC CGL 12/04/2022 (Evening) 
 (a) green  (b) blue   (c) red  (d) orange 
 Sol.17.(b)  Blue  .  So  gold  and  copper  are 
 yellowish  in  color.  Gold  (Au,  Group  11, 
 Atomic  number  79).  Silver  (Ag,  Group  11, 
 Atomic number 47). 
 Q.18.  The absolute refractive index of 
 ______ is 2.42. 
 SSC MTS 07/10/2021 (Evening) 
 (a) air  (b) diamond 
 (c) crown glass  (d) water 
 Sol.18.(b)  Diamond.  Refractive  index 
 measures  the  bending  of  a  ray  of  light 
 when  passing  from  one  medium  into 
 another.  The  refractive  index  of  a 
 substance  is  described  by  the  formula,  n 
 =  c/v,  where  c  is  the  speed  of  light  in 
 vacuum  (3  ×  10 
 8 
 m/s)  and  v  is  the  phase 
 velocity  of  light.  Refractive  Index  -  Air  - 
 1.0003,  Water  -  1.333,  Diamond  -  2.417, 
 Ice- 1.31, Ethyl Alcohol - 1.36, Vacuum- 1. 
 Q.19.  Apart  from  the  red  and  green 
 wavelengths  of  sunlight,  which  other 
 wavelength  of  sunlight  is  absorbed  by 
 water molecules in the ocean? 
 SSC MTS 08/10/2021 (Morning) 
 (a) Orange  (b) Blue  (c) Violet  (d) Yellow 
 Sol.19.(d)  Yellow  .  When  sunlight  hits  the 
 ocean,  some  of  the  light  is  re?ected  back 
 directly  but  most  of  it  penetrates  the 
 ocean  surface  and  interacts  with  the 
 water molecules. 
 Q.20.  Which  of  the  following  types  of 
 mirrors show a lateral inversion of light? 
 SSC MTS 13/10/2021 (Afternoon) 
 (a) Convex mirror        (b) Concave mirror 
 (c) Rectangle mirror   (d) Plane mirror 
 Sol.20.(d)  Plane  mirror  .  Lateral  inversion 
 is  the  reversal  of  a  mirror  image  where 
 the  right  side  of  the  object  appears  on 
 the  left  side  behind  the  mirror. 
 Characteristics  of  a  plane  mirror  -  Image 
 are  Virtual  and  Erect.  Image  is  formed 
 behind  the  mirror.  Size  of  the  image  is 
 equal.  Distance  of  image  and  mirror  is 
 equal  to  the  distance  of  object  and 
 mirror. 
 Q.21.  The  color  of  the  clear  sky  is  blue 
 due to the phenomenon of: 
 SSC MTS 18/10/2021 (Morning) 
 (a) dispersion of light (b) re?ection of light 
 (c) scattering of light  (d) refraction of light 
 Sol.21.(c)  Scattering  of  light  .  CV  Raman 
 was  awarded  the  Nobel  prize  in  Physics 
 in  1930  for  his  discovery  of  Raman  effect 
 (Scattering  of  light).  The  Tyndall  effect  is 
 the  phenomenon  of  the  scattering  of 
 light by colloidal particles. 
 Q.22.  What is the full form of LED? 
 SSC MTS 27/10/2021 (Morning) 
 (a) Linear Emergency Device 
 (b) Light Emitting Diode 
 (c) Liquid Emitting Display 
 (d) Light Emitting Device 
 Sol.22.(b)  Light-emitting Diode  (LED) -  A 
 semiconductor device, which can emit 
 light when an electric current passes 
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Page 3


 Pinnacle  Physics 
 Physics 
 Light and Optics 
 Q.1.  A  concave  spherical  mirror  has  a 
 radius  of  curvature  of  30  cm.  An  object 
 was  placed  15  cm  away  from  the  pole  in 
 front  of  the  mirror  on  the  principal  axis. 
 Choose  the  correct  option  for  the 
 position,  size  and  nature  of  the  image 
 formed, respectively. 
 SSC Stenographer 13/10/2023 (Morning) 
 (a) Behind the mirror, enlarged, virtual 
 and erect 
 (b) At in?nity, highly enlarged, real and 
 inverted 
 (c) Between Focus and Centre, 
 diminished, real and inverted 
 (d) At the focus, highly diminished 
 point-sized, real and inverted 
 Sol.1.(b)  At  In?nity,  highly  enlarged,  real 
 and  inverted.  We  know  that,  focus  of  a 
 mirror,  f  =  R/2,  where  R  is  the  radius  of 
 curvature  of  the  mirror.  Here  in  this  case, 
 f  =  -  30/2  =  -15  cm.  Also,  distance  of  the 
 object  from  the  mirror,  u  =  -15  cm.  It 
 means  that  the  object  is  placed  at  the 
 focus  of  the  mirror.  Now  it  is  clear  that 
 when  the  object  is  placed  at  focus  of  the 
 mirror,  the  respective  image  will  be 
 formed  at  in?nity.  The  size  of  the  image 
 would  be  highly  enlarged.  The  nature  of 
 the image would be real and inverted. 
 Q.2.  In  optics,  which  term  refers  to  the 
 opening  of  the  diaphragm  of  a  lens  that 
 spatially limits the propagation of light ? 
 SSC MTS 13/09/2023 (1st Shift) 
 (a) Collimator  (b) Aperture 
 (c) Apostilb  (d) Meniscus 
 Sol.2.(b)  Aperture.  Collimator  -  A  device 
 which  narrows  a  beam  of  particles  or 
 waves.  Apostilb  -  An  obsolete  unit  of 
 luminance.  Meniscus  -  A  C-shaped  piece 
 of  tough,  rubbery  cartilage  that  acts  as  a 
 shock  absorber  between  the  shinbone 
 and the thigh bone. 
 Q.3.  White light is an example of: 
 SSC CHSL 04/08/2023 (2nd shift) 
 (a) laser light 
 (b) plane polarized light 
 (c) monochromatic light 
 (d) polychromatic light 
 Sol.3.(d)  Polychromatic  light  -  The  light 
 consists  of  a  broad  range  of 
 wavelengths.  Examples  -  Mercury  Light, 
 Sunlight,  laser-pumped  plasma  light. 
 Monochromatic  light  -  The  light  consists 
 of  only  one  speci?c  wavelength. 
 Examples  -  laser  beam,  Sodium  lamps, 
 Spark  lamps.  Plane  polarized  light  -  It 
 consists  of  waves  in  which  the  direction 
 of  vibration  is  the  same  for  all  waves. 
 Examples  -  laser  lights  and  devices. 
 Laser  light  -  Laser  (Light  Ampli?cation  by 
 Stimulated  Emission  of  Radiation)  is  an 
 arti?cial  source  of  light  radiation  that 
 emits  a  coherent  beam  of  photons,  as 
 the  source  is  stable  in  frequency, 
 wavelength, and power. 
 Q.4.  Which  telescope  was  invented  by 
 Isaac  Newton  in  the  17th  century  by 
 using  a  concave  mirror  to  collect  light 
 instead  of  a  simple  lens  which  produces 
 false  colors  due  to  the  dispersion  of 
 light? 
 SSC CHSL 09/08/2023 (3rd shift) 
 (a) Re?ecting telescope 
 (b) Infrared telescope 
 (c) Monocular telescope 
 (d) Graphic telescope 
 Sol.4.(a)  Re?ecting  telescope  -  Uses 
 mirrors  which  cause  light  to  re?ect  at 
 different  angles  within  the  optical  tube 
 and  extends  the  overall  light  path.  Two 
 major  types  of  telescopes  :  Re?ecting 
 Telescopes  and  Refracting  Telescopes 
 (used  lenses  to  magnify  objects). 
 Infrared  telescope  :  Uses  infrared  light  to 
 detect celestial bodies. 
 Q.5.  The  minimum  distance  of  distinct 
 vision  for  a  young  adult  person  with  no 
 defect in eyes is: 
 SSC CHSL 11/08/2023 (4th shift) 
 (a) 20 m  (b) 25 cm  (c) 20 cm  (d) 25 m 
 Sol.5.(b)  25  cm.  For  a  normal  eye,  the  far 
 point  is  at  in?nity  and  the  near  point  of 
 distinct  vision  is  about  25  cm  in  front  of 
 the  eye.  Hypermetropia  (far-sightedness) 
 :  When  the  point  goes  farther  from  25 
 cm.  Lens  used  :  Convex.  Myopia 
 (Nearsightedness):  Near  objects  appear 
 clear,  but  objects  farther  away  look 
 blurry. Lens used: Concave. 
 Q.6.  Which  colour  of  light  from  VIBGYOR 
 has minimum energy ? 
 SSC CHSL 14/08/2023 (1st shift) 
 (a) Green (b) Violet (c) Yellow (d) Red 
 Sol.6.(d)  Red  .  It  has  the  longest 
 wavelength  and  least  energy  of  the 
 visible  colors  of  light.  Wavelength  -  The 
 distance  between  two  successive  crests 
 or  troughs.  Violet  has  the  shortest 
 wavelength.  Frequency  -  It  refers  to  the 
 number  of  waves  passing  through  a 
 point  per  second.  Violet  has  the  highest 
 frequency.  The  white  light  consists  of  7 
 colors  VIBGYOR  (Violet  -  Indigo  -  Blue  - 
 Green - Yellow - Orange - Red). 
 Q.7.  Why  can  you  not  see  objects  in  a 
 dim  lit  room  when  you  come  from  a 
 brightly lit room? 
 SSC CGL 25/07/2023 (4th shift) 
 (a) The iris dilates the eye lens to allow 
 less light to enter the eye. 
 (b) The iris contracts the pupil to allow 
 less light to enter the eye. 
 (c) The vitreous humour dilates the pupil 
 to allow less light to enter the eye. 
 (d) The cornea contracts the pupil to 
 allow less light to enter the eye. 
 Sol.7.(b)  Iris  -  It  gives  a  distinct  color  to 
 the  eyes.  The  eyeball  is  spherical  in 
 shape  having  a  diameter  of  23  mm. 
 Vitreous  humor  present  in  between  lens 
 and  retina.  Retina  contains  three  layers 
 of  neural  cells  (ganglion  cells,  bipolar 
 cells,  photoreceptor  cells).  Cornea  -  The 
 front  most  and  transparent  covering  of 
 the  eye.  Light  enters  the  human  eye 
 through the cornea. 
 Q.8.  What  will  be  the  focal  length  of  a 
 convex  lens  with  the  power  of  a  +2.5 
 Diopter? 
 Higher Secondary 28/06/2023 ( Shift - 2) 
 (a) 20 cm (b) 10 cm (c) 40 cm (d) 5 cm 
 Sol.8.(c) 40 cm.  Using the formula: 
 focal  length  (f)  of  convex  Lens  =  1/Power 
 (P) 
 Given,  the power (P) =  +2.5 diopters 
 then  focal  length:  f  =  1  /  2.5  =  0.4  meters 
 =  40  centimeters  .  Focal  length  of  convex 
 lens  is  always  positive  and  concave  lens 
 is always negative. 
 Q.9.  Raman  wants  to  use  a  rear-view 
 mirror  in  his  vehicle.  Which  type  of 
 mirror should he pick for it ? 
 SSC CHSL 10/03/2023 (2nd Shift) 
 (a) Convex Mirrors       (b) Plane Mirrors 
 (c) Cylindrical Mirrors  (d) Concave Mirrors 
 Sol.9.(a)  Convex  Mirrors.  This  is 
 because  they  give  an  erect,  virtual,  full 
 size  diminished  image  of  distant  objects 
 with  a  wider  ?eld  of  view.  Uses  - 
 Sunglasses, street lights. 
 Q.10.  An  image  formed  by  the  convex 
 mirror is always _________. 
 SSC CHSL 14/03/2023 (3rd Shift) 
 (a) virtual and inverted (b) real and erect 
 (c) virtual and erect      (d) real and inverted 
 Sol.10.(c)  Virtual  and  erect.  Convex 
 mirror  (Diverging  Mirror)  -  It  has  a 
 re?ecting  surface  that  bulges  outwards, 
 and  away  from  the  centre  of  curvature. 
 Uses  -  Rear  view  mirrors,  Street  light 
 re?ector, etc. 
 Q.11.  Which of the following statements 
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 Pinnacle  Physics 
 regarding the lenses is/are correct? 
 I. Power of a convex lens is represented 
 as a positive number. 
 II. Power of a concave lens is 
 represented as a negative number. 
 SSC CHSL 17/03/2023 (4th Shift) 
 (a) Both I and II  (b) Only II 
 (c) Only I  (d) Neither I nor II 
 Sol.11.(a)  Both  I  and  II.  The  focal  length  of 
 the  convex  lens  is  always  positive.  The 
 power  of  the  lens  = 
 .  If  the  focal  length 
 1 
 ??????????     ??????????h ( ????     ?????????? )
 is  positive,  then  power  is  always  positive. 
 Uses  of  convex  lens  -  Magnifying  glasses, 
 Eyeglasses, Cameras, Microscopes etc. 
 A  concave  lens  (diverging  lens)  diverges 
 the  rays  incident  on  it.  Its  power  is 
 negative.  Uses  of  concave  lenses  - 
 telescopes, lasers etc. 
 Q.12.  Which  of  the  following  pair  of 
 position  of  object  –  position  of  image  – 
 size  of  image,  is  NOT  correct  for  concave 
 mirror? 
 SSC CPO 10/11/2022 (Morning) 
 (a) At F - At in?nity - Highly enlarged 
 (b) Between C and F - Beyond C - 
 Enlarged 
 (c) Beyond C - Between F and C - 
 Diminished 
 (d) At in?nity - At C - Highly diminished 
 Sol.12.(d)  At  in?nity  -  At  C  -  Highly 
 diminished.  Spherical  mirrors  are  of  two 
 types,  concave  and  convex.  Image 
 formation  by  Concave  Mirror  (Object 
 Position  -  Image  Position  -  Image  Nature 
 and  Size)  :  (At  In?nity  -  At  F  -  Real,  point 
 size);  (Beyond  Center  C  -  Between  C  and 
 F  (Focus)  -  Diminished,  Real  and 
 Inverted);  (On  Centre  -  Real,  inverted,  and 
 same  size);  (Between  Centre  (C)  and 
 Focus  (F)  -  Beyond  Centre  -  Real, 
 inverted,  and  larger);  (on  Focus  -  In?nity  - 
 Real,  inverted,  and  enlarged);  (On  Focal 
 length  (Between  Pole  and  Focus)  - 
 Behind  Mirror  -  Virtual,  straight  and 
 enlarged). 
 Q.13.  If  ‘u’  is  the  object-distance,  ‘v’  is  the 
 image-distance  and  ‘f’  is  the  focal  length 
 of  a  spherical  mirror  then  which  of  the 
 following  is  a  correct  expression  for  the 
 mirror formula? 
 SSC MTS 07/07/2022 (Morning) 
 (a) 1/v + 1/u = –1/f    (b) 1/v – 1/u = 1/f 
 (c) 1/v + 1/u = 1/f       (d) 1/v – 1/u = –1/f 
 Sol.13.(c)  1/v  +  1/u  =  1/f  .  There  are  two 
 types  of  spherical  mirrors  :  concave 
 mirrors  (If  the  re?ective  surface  is  on  the 
 side  curved  inwards)  and  convex  mirrors 
 (if the re?ective surface is curved 
 outwards). The  lens formula  is 1/v-1/u 
 = 1/f. 
 Q.14.  The  splitting  of  white  light  into  its 
 component colours is called ______. 
 SSC MTS 12/07/2022 (Morning) 
 (a) refraction  (b) re?ection 
 (c) scattering  (d) dispersion 
 Sol.14.(d)  Dispersion  .  Refraction  - 
 Redirection  of  a  wave  as  it  passes  from 
 one  medium  to  another.  Re?ection  - 
 When  a  ray  of  light  approaches  a  smooth 
 polished surface, it bounces back. 
 Q.15.  The  re?ection  on  a  bathroom 
 mirror,  the  lake,  and  the  glare  on  a  pair  of 
 glasses  are  caused  by  which  type  of 
 re?ection? 
 SSC CHSL 03/06/2022 (Evening) 
 (a) Multiple re?ection 
 (b) Specular re?ection 
 (c) Glossy re?ection 
 (d) Diffused re?ection 
 Sol.15.(b)  Specular  re?ection  is  de?ned 
 as  light  re?ected  from  a  smooth  surface 
 at  a  de?nite  angle  like  a  re?ection  on  a 
 bathroom  mirror.  Diffuse  re?ection  is 
 produced  by  rough  surfaces  that  tend  to 
 re?ect  light  in  all  directions  like  reading  a 
 newspaper.  Multiple  re?ections,  when 
 we  take  two  mirrors,  a  single  source  of 
 light  can  be  re?ected  multiple  times  like 
 in  a  barber's  shop,  we  see  the  back  of  the 
 head  using  multiple  re?ections  of  two 
 mirrors. 
 Q.16.  Which  of  the  following  elements  is 
 NOT  suitable  for  the  fabrication  of  a  light 
 emitting diode structure? 
 SSC CGL 12/04/2022 (Afternoon) 
 (a) Gallium phosphide 
 (b) Indium gallium nitride 
 (c) Germanium 
 (d) Gallium arsenide 
 Sol.16.(c)  Germanium  (Group  14,  Atomic 
 number  32)  -  It  is  a  semiconductor 
 (properties  between  the  metals  and  the 
 non-metals).  Uses  -  as  a  transistor,  used 
 in  wide-angle  camera  lenses  and 
 objective lenses for microscopes. 
 Q.17  .  Gold  and  copper  happen  to  absorb 
 ______and violet light, leaving yellow light. 
 SSC CGL 12/04/2022 (Evening) 
 (a) green  (b) blue   (c) red  (d) orange 
 Sol.17.(b)  Blue  .  So  gold  and  copper  are 
 yellowish  in  color.  Gold  (Au,  Group  11, 
 Atomic  number  79).  Silver  (Ag,  Group  11, 
 Atomic number 47). 
 Q.18.  The absolute refractive index of 
 ______ is 2.42. 
 SSC MTS 07/10/2021 (Evening) 
 (a) air  (b) diamond 
 (c) crown glass  (d) water 
 Sol.18.(b)  Diamond.  Refractive  index 
 measures  the  bending  of  a  ray  of  light 
 when  passing  from  one  medium  into 
 another.  The  refractive  index  of  a 
 substance  is  described  by  the  formula,  n 
 =  c/v,  where  c  is  the  speed  of  light  in 
 vacuum  (3  ×  10 
 8 
 m/s)  and  v  is  the  phase 
 velocity  of  light.  Refractive  Index  -  Air  - 
 1.0003,  Water  -  1.333,  Diamond  -  2.417, 
 Ice- 1.31, Ethyl Alcohol - 1.36, Vacuum- 1. 
 Q.19.  Apart  from  the  red  and  green 
 wavelengths  of  sunlight,  which  other 
 wavelength  of  sunlight  is  absorbed  by 
 water molecules in the ocean? 
 SSC MTS 08/10/2021 (Morning) 
 (a) Orange  (b) Blue  (c) Violet  (d) Yellow 
 Sol.19.(d)  Yellow  .  When  sunlight  hits  the 
 ocean,  some  of  the  light  is  re?ected  back 
 directly  but  most  of  it  penetrates  the 
 ocean  surface  and  interacts  with  the 
 water molecules. 
 Q.20.  Which  of  the  following  types  of 
 mirrors show a lateral inversion of light? 
 SSC MTS 13/10/2021 (Afternoon) 
 (a) Convex mirror        (b) Concave mirror 
 (c) Rectangle mirror   (d) Plane mirror 
 Sol.20.(d)  Plane  mirror  .  Lateral  inversion 
 is  the  reversal  of  a  mirror  image  where 
 the  right  side  of  the  object  appears  on 
 the  left  side  behind  the  mirror. 
 Characteristics  of  a  plane  mirror  -  Image 
 are  Virtual  and  Erect.  Image  is  formed 
 behind  the  mirror.  Size  of  the  image  is 
 equal.  Distance  of  image  and  mirror  is 
 equal  to  the  distance  of  object  and 
 mirror. 
 Q.21.  The  color  of  the  clear  sky  is  blue 
 due to the phenomenon of: 
 SSC MTS 18/10/2021 (Morning) 
 (a) dispersion of light (b) re?ection of light 
 (c) scattering of light  (d) refraction of light 
 Sol.21.(c)  Scattering  of  light  .  CV  Raman 
 was  awarded  the  Nobel  prize  in  Physics 
 in  1930  for  his  discovery  of  Raman  effect 
 (Scattering  of  light).  The  Tyndall  effect  is 
 the  phenomenon  of  the  scattering  of 
 light by colloidal particles. 
 Q.22.  What is the full form of LED? 
 SSC MTS 27/10/2021 (Morning) 
 (a) Linear Emergency Device 
 (b) Light Emitting Diode 
 (c) Liquid Emitting Display 
 (d) Light Emitting Device 
 Sol.22.(b)  Light-emitting Diode  (LED) -  A 
 semiconductor device, which can emit 
 light when an electric current passes 
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 Pinnacle  Physics 
 through  it.  Working  principle  - 
 Electroluminescence. 
 Q.23.  Which  phenomenon  deals  with  the 
 scattering  of  light  by  molecules  of  a 
 medium  when  they  are  excited  to 
 vibrational energy levels? 
 SSC CGL 24/08/2021 (Evening) 
 (a) Huygens Effect   (b) Maxwell Effect 
 (c) Raman Effect      (d) Rayleigh Effect 
 Sol.23.(c)  Raman  Effect.  Huygens' 
 principle  states  that  every  point  on  a 
 wavefront  may  be  considered  as  a 
 source  of  secondary  waves.  Maxwell 
 Effect  is  a  phenomenon  of 
 electromagnetic  induction  in  which  an 
 electric  charge,  near  a  solenoid  in  which 
 current  changes  slowly,  feels  an 
 electromotive  force  (e.m.f.)  even  if  the 
 magnetic  ?eld  is  practically  static  inside 
 and  null  outside.  Rayleigh  Effect  is  a 
 phenomenon  of  scattering  of  light  or 
 other  electromagnetic  radiation  by 
 particles  much  smaller  than  the 
 wavelength of the radiation. 
 Q.24.  The  phenomenon  of  deviation  of 
 light  rays  from  their  original  path,  when 
 they  pass  from  one  medium  to  another, 
 is called ____. 
 SSC CPO 25/11/2020 (Evening) 
 (a) obstruction  (b) re?ection 
 (c) Diffraction  (d) Refraction 
 Sol.24.(d)  Refraction.  When  light  moves 
 from  rarer  (air)  to  a  denser  medium 
 (water),  it  bends  towards  the  normal  and 
 if  it  moves  from  a  denser  to  a  rarer 
 medium, it bends away from the normal. 
 Q.25.  What  is  the  name  of  the 
 phenomena  (derived  by  scattering  of  the 
 light)  in  which  mountain  tops  acquire  a 
 rosy  or  orange  hue  around  sunrise  and 
 sunset ? 
 SSC CGL 04/03/2020 (Evening) 
 (a) Brillouin scattering 
 (b) Circle of confusion 
 (c) Alpenglow 
 (d) Barrel distortion 
 Sol.25.(c)  Alpenglow  .  It  is  either  the 
 indirect  sunlight  re?ection  off  of  clouds 
 after  sunset  or  before  sunrise,  or  to 
 direct  sunlight  that  occurs  near  sunset  or 
 sunrise. 
 Q.26.  The  total  number  of  images 
 formed  by  two  mirrors  inclined  at  120°  to 
 each other is ______. 
 SSC CGL 05/03/2020 (Afternoon) 
 (a) 1  (b) 2  (c) 4  (d) 3 
 Sol.26.(b) 2.  The number of images 
 formed when  two mirrors  are placed at 
 an  angle  theta  (  )  to  each  other  is  given ?
 by :  n = (360° /  ) - 1 ?
 So,  here,  we  have  the  mirrors  placed  at 
 an angle  = 120° ?
 n = no. of images formed ?
 n = ( 360° /120° ) - 1 ?
 n = 3 - 1  n = 2 ? ?
 So, a total of two images will be formed. 
 Heat and Thermodynamics 
 Q.27  .  Which  of  the  following  best 
 describes the process of calorimetry? 
 SSC MTS 14/09/2023 (3rd Shift) 
 (a) Measuring the amount of 
 compressive strength 
 (b) Measuring the amount of force 
 (c) Measuring the amount of electricity 
 (d) Measuring the amount of heat energy 
 transferred 
 Sol.27.(d)  Calorimetry  is  the  process  of 
 measuring  the  amount  of  heat  released 
 or  absorbed  during  a  chemical  reaction. 
 By  knowing  the  change  in  heat,  it  can  be 
 determined  whether  or  not  a  reaction  is 
 exothermic  (releases  heat)  or 
 endothermic  (absorbs  heat).  Calorimetry 
 also  plays  a  large  part  of  everyday  life, 
 controlling  the  metabolic  rates  in 
 humans  and  consequently  maintaining 
 such functions like body temperature. 
 Q.28.  In  which  method  of  cooking  is  food 
 heated  slowly  over  a  source  of  heat  and 
 cooked  by  high  heat  and  air  convection 
 depending  on  the  position  of  the  food  in 
 relation to the ?re? 
 SSC CGL 26/07/2023 (2nd shift) 
 (a) Spit-roasting  (b) Braising 
 (c) Poaching  (d) Stewing 
 Sol.28.(a)  Spit-roasting.  Braising  -  The 
 cooking  of  meat  or  vegetables  by  heating 
 them  slowly  with  oil  and  moisture  in  a 
 tightly  sealed  vessel.  Poaching  -  A  moist 
 heat  method  of  cooking  by  submerging 
 food  in  some  kind  of  liquid  and  heating 
 at  a  low  temperature.  Stewing  -  A 
 combination  cooking  method  that  uses 
 small,  uniform  pieces  of  meat  that  are 
 totally  immersed  in  liquid  and  slowly 
 simmered. 
 Q.29.  Who coined the term 'zeroth law of 
 thermodynamics'  in  1931,  which  asserts 
 that  two  bodies  in  equilibrium  with  a  third 
 are in equilibrium with each other? 
 SSC CGL 27/07/2023 (3rd shift) 
 (a) James Clerk Maxwell 
 (b) Max Planck 
 (c) Josiah Willard Gibbs 
 (d) Ralph H. Fowler 
 Sol.29.(d) Ralph H Fowler. 
 Thermodynamics  deals  with  the  relations 
 between  heat  and  other  forms  of  energy. 
 James  Clerk  Maxwell  -  Theory  of 
 electromagnetism.  Max  Planck  -  The 
 quantum  of  action  (Planck's  constant). 
 Josiah  Willard  Gibbs  -  Gibbs  energy 
 (Available energy in a system). 
 Q.30.  Triple point can be de?ned as: 
 Matric Level 28/06/2023 (Shift - 1) 
 (a) the condition of temperature under 
 which the gaseous and liquid phases 
 of a substance can exist in 
 equilibrium 
 (b) the temperature at which solid is 
 converted into liquid 
 (c) the condition of pressure under which 
 the solid and liquid phases of a 
 substance can exist in equilibrium 
 (d) the condition of temperature and 
 pressure under which the gaseous, 
 liquid and solid phases of a 
 substance can exist in equilibrium 
 Sol.30.(d)  The  triple  point  of  water  is  at 
 273.16  kelvin  (0.01  °C  or  32.02  °F)  and  a 
 pressure of 611.7 Pascals. 
 Q.31.  According  to  law,  heat 
 produced  by  an  electric  current  is  directly 
 proportional  to  the  resistance  of  the 
 conductor,  the  square  of  the  current,  and 
 the time for which it ?ows. 
 SSC MTS 17/05/2023 (Afternoon) 
 (a) Hooke's  (b) Charles's 
 (c) Faraday's  (d) Joule's 
 Sol.31.(d)  Joule's.  Joule's  law  of  heating, 
 H  =  I 
 2 
 RT,  where,  H  -  Heat,  I  -  Current,  R  - 
 Resistance,  T  -  time.  Hooke's  law  (law  of 
 elasticity)  -  Discovered  by  the  English 
 scientist  Robert  Hooke  in  1660,  which 
 states  that,  for  relatively  small 
 deformations  of  an  object,  the 
 displacement  or  size  of  the  deformation 
 is  directly  proportional  to  the  deforming 
 force  or  load.  Faraday's  law  -  The 
 magnitude  of  induced  emf  is  equal  to  the 
 rate  of  change  of  ?ux  linkages  with  the 
 coil. 
 Q.32.  Tensile  or  compressive  stress  can 
 also be termed as _______. 
 SSC MTS 13/06/2023 (Morning) 
 (a) longitudinal stress 
 (b) tangential stress 
 (c) hydraulic stress 
 (d) shearing stress 
 Sol.32.(a)  Longitudinal  stress  (axial 
 stress)  .  Other  types  of  stress  :  Tangential 
 stress  is  a  type  of  stress  that  acts 
 perpendicular  to  the  surface  of  an  object. 
 Hydraulic  stress  is  a  type  of  stress  that  is 
 caused  by  the  pressure  of  a  ?uid. 
 Shearing stress is a type of stress that 
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Page 4


 Pinnacle  Physics 
 Physics 
 Light and Optics 
 Q.1.  A  concave  spherical  mirror  has  a 
 radius  of  curvature  of  30  cm.  An  object 
 was  placed  15  cm  away  from  the  pole  in 
 front  of  the  mirror  on  the  principal  axis. 
 Choose  the  correct  option  for  the 
 position,  size  and  nature  of  the  image 
 formed, respectively. 
 SSC Stenographer 13/10/2023 (Morning) 
 (a) Behind the mirror, enlarged, virtual 
 and erect 
 (b) At in?nity, highly enlarged, real and 
 inverted 
 (c) Between Focus and Centre, 
 diminished, real and inverted 
 (d) At the focus, highly diminished 
 point-sized, real and inverted 
 Sol.1.(b)  At  In?nity,  highly  enlarged,  real 
 and  inverted.  We  know  that,  focus  of  a 
 mirror,  f  =  R/2,  where  R  is  the  radius  of 
 curvature  of  the  mirror.  Here  in  this  case, 
 f  =  -  30/2  =  -15  cm.  Also,  distance  of  the 
 object  from  the  mirror,  u  =  -15  cm.  It 
 means  that  the  object  is  placed  at  the 
 focus  of  the  mirror.  Now  it  is  clear  that 
 when  the  object  is  placed  at  focus  of  the 
 mirror,  the  respective  image  will  be 
 formed  at  in?nity.  The  size  of  the  image 
 would  be  highly  enlarged.  The  nature  of 
 the image would be real and inverted. 
 Q.2.  In  optics,  which  term  refers  to  the 
 opening  of  the  diaphragm  of  a  lens  that 
 spatially limits the propagation of light ? 
 SSC MTS 13/09/2023 (1st Shift) 
 (a) Collimator  (b) Aperture 
 (c) Apostilb  (d) Meniscus 
 Sol.2.(b)  Aperture.  Collimator  -  A  device 
 which  narrows  a  beam  of  particles  or 
 waves.  Apostilb  -  An  obsolete  unit  of 
 luminance.  Meniscus  -  A  C-shaped  piece 
 of  tough,  rubbery  cartilage  that  acts  as  a 
 shock  absorber  between  the  shinbone 
 and the thigh bone. 
 Q.3.  White light is an example of: 
 SSC CHSL 04/08/2023 (2nd shift) 
 (a) laser light 
 (b) plane polarized light 
 (c) monochromatic light 
 (d) polychromatic light 
 Sol.3.(d)  Polychromatic  light  -  The  light 
 consists  of  a  broad  range  of 
 wavelengths.  Examples  -  Mercury  Light, 
 Sunlight,  laser-pumped  plasma  light. 
 Monochromatic  light  -  The  light  consists 
 of  only  one  speci?c  wavelength. 
 Examples  -  laser  beam,  Sodium  lamps, 
 Spark  lamps.  Plane  polarized  light  -  It 
 consists  of  waves  in  which  the  direction 
 of  vibration  is  the  same  for  all  waves. 
 Examples  -  laser  lights  and  devices. 
 Laser  light  -  Laser  (Light  Ampli?cation  by 
 Stimulated  Emission  of  Radiation)  is  an 
 arti?cial  source  of  light  radiation  that 
 emits  a  coherent  beam  of  photons,  as 
 the  source  is  stable  in  frequency, 
 wavelength, and power. 
 Q.4.  Which  telescope  was  invented  by 
 Isaac  Newton  in  the  17th  century  by 
 using  a  concave  mirror  to  collect  light 
 instead  of  a  simple  lens  which  produces 
 false  colors  due  to  the  dispersion  of 
 light? 
 SSC CHSL 09/08/2023 (3rd shift) 
 (a) Re?ecting telescope 
 (b) Infrared telescope 
 (c) Monocular telescope 
 (d) Graphic telescope 
 Sol.4.(a)  Re?ecting  telescope  -  Uses 
 mirrors  which  cause  light  to  re?ect  at 
 different  angles  within  the  optical  tube 
 and  extends  the  overall  light  path.  Two 
 major  types  of  telescopes  :  Re?ecting 
 Telescopes  and  Refracting  Telescopes 
 (used  lenses  to  magnify  objects). 
 Infrared  telescope  :  Uses  infrared  light  to 
 detect celestial bodies. 
 Q.5.  The  minimum  distance  of  distinct 
 vision  for  a  young  adult  person  with  no 
 defect in eyes is: 
 SSC CHSL 11/08/2023 (4th shift) 
 (a) 20 m  (b) 25 cm  (c) 20 cm  (d) 25 m 
 Sol.5.(b)  25  cm.  For  a  normal  eye,  the  far 
 point  is  at  in?nity  and  the  near  point  of 
 distinct  vision  is  about  25  cm  in  front  of 
 the  eye.  Hypermetropia  (far-sightedness) 
 :  When  the  point  goes  farther  from  25 
 cm.  Lens  used  :  Convex.  Myopia 
 (Nearsightedness):  Near  objects  appear 
 clear,  but  objects  farther  away  look 
 blurry. Lens used: Concave. 
 Q.6.  Which  colour  of  light  from  VIBGYOR 
 has minimum energy ? 
 SSC CHSL 14/08/2023 (1st shift) 
 (a) Green (b) Violet (c) Yellow (d) Red 
 Sol.6.(d)  Red  .  It  has  the  longest 
 wavelength  and  least  energy  of  the 
 visible  colors  of  light.  Wavelength  -  The 
 distance  between  two  successive  crests 
 or  troughs.  Violet  has  the  shortest 
 wavelength.  Frequency  -  It  refers  to  the 
 number  of  waves  passing  through  a 
 point  per  second.  Violet  has  the  highest 
 frequency.  The  white  light  consists  of  7 
 colors  VIBGYOR  (Violet  -  Indigo  -  Blue  - 
 Green - Yellow - Orange - Red). 
 Q.7.  Why  can  you  not  see  objects  in  a 
 dim  lit  room  when  you  come  from  a 
 brightly lit room? 
 SSC CGL 25/07/2023 (4th shift) 
 (a) The iris dilates the eye lens to allow 
 less light to enter the eye. 
 (b) The iris contracts the pupil to allow 
 less light to enter the eye. 
 (c) The vitreous humour dilates the pupil 
 to allow less light to enter the eye. 
 (d) The cornea contracts the pupil to 
 allow less light to enter the eye. 
 Sol.7.(b)  Iris  -  It  gives  a  distinct  color  to 
 the  eyes.  The  eyeball  is  spherical  in 
 shape  having  a  diameter  of  23  mm. 
 Vitreous  humor  present  in  between  lens 
 and  retina.  Retina  contains  three  layers 
 of  neural  cells  (ganglion  cells,  bipolar 
 cells,  photoreceptor  cells).  Cornea  -  The 
 front  most  and  transparent  covering  of 
 the  eye.  Light  enters  the  human  eye 
 through the cornea. 
 Q.8.  What  will  be  the  focal  length  of  a 
 convex  lens  with  the  power  of  a  +2.5 
 Diopter? 
 Higher Secondary 28/06/2023 ( Shift - 2) 
 (a) 20 cm (b) 10 cm (c) 40 cm (d) 5 cm 
 Sol.8.(c) 40 cm.  Using the formula: 
 focal  length  (f)  of  convex  Lens  =  1/Power 
 (P) 
 Given,  the power (P) =  +2.5 diopters 
 then  focal  length:  f  =  1  /  2.5  =  0.4  meters 
 =  40  centimeters  .  Focal  length  of  convex 
 lens  is  always  positive  and  concave  lens 
 is always negative. 
 Q.9.  Raman  wants  to  use  a  rear-view 
 mirror  in  his  vehicle.  Which  type  of 
 mirror should he pick for it ? 
 SSC CHSL 10/03/2023 (2nd Shift) 
 (a) Convex Mirrors       (b) Plane Mirrors 
 (c) Cylindrical Mirrors  (d) Concave Mirrors 
 Sol.9.(a)  Convex  Mirrors.  This  is 
 because  they  give  an  erect,  virtual,  full 
 size  diminished  image  of  distant  objects 
 with  a  wider  ?eld  of  view.  Uses  - 
 Sunglasses, street lights. 
 Q.10.  An  image  formed  by  the  convex 
 mirror is always _________. 
 SSC CHSL 14/03/2023 (3rd Shift) 
 (a) virtual and inverted (b) real and erect 
 (c) virtual and erect      (d) real and inverted 
 Sol.10.(c)  Virtual  and  erect.  Convex 
 mirror  (Diverging  Mirror)  -  It  has  a 
 re?ecting  surface  that  bulges  outwards, 
 and  away  from  the  centre  of  curvature. 
 Uses  -  Rear  view  mirrors,  Street  light 
 re?ector, etc. 
 Q.11.  Which of the following statements 
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 Pinnacle  Physics 
 regarding the lenses is/are correct? 
 I. Power of a convex lens is represented 
 as a positive number. 
 II. Power of a concave lens is 
 represented as a negative number. 
 SSC CHSL 17/03/2023 (4th Shift) 
 (a) Both I and II  (b) Only II 
 (c) Only I  (d) Neither I nor II 
 Sol.11.(a)  Both  I  and  II.  The  focal  length  of 
 the  convex  lens  is  always  positive.  The 
 power  of  the  lens  = 
 .  If  the  focal  length 
 1 
 ??????????     ??????????h ( ????     ?????????? )
 is  positive,  then  power  is  always  positive. 
 Uses  of  convex  lens  -  Magnifying  glasses, 
 Eyeglasses, Cameras, Microscopes etc. 
 A  concave  lens  (diverging  lens)  diverges 
 the  rays  incident  on  it.  Its  power  is 
 negative.  Uses  of  concave  lenses  - 
 telescopes, lasers etc. 
 Q.12.  Which  of  the  following  pair  of 
 position  of  object  –  position  of  image  – 
 size  of  image,  is  NOT  correct  for  concave 
 mirror? 
 SSC CPO 10/11/2022 (Morning) 
 (a) At F - At in?nity - Highly enlarged 
 (b) Between C and F - Beyond C - 
 Enlarged 
 (c) Beyond C - Between F and C - 
 Diminished 
 (d) At in?nity - At C - Highly diminished 
 Sol.12.(d)  At  in?nity  -  At  C  -  Highly 
 diminished.  Spherical  mirrors  are  of  two 
 types,  concave  and  convex.  Image 
 formation  by  Concave  Mirror  (Object 
 Position  -  Image  Position  -  Image  Nature 
 and  Size)  :  (At  In?nity  -  At  F  -  Real,  point 
 size);  (Beyond  Center  C  -  Between  C  and 
 F  (Focus)  -  Diminished,  Real  and 
 Inverted);  (On  Centre  -  Real,  inverted,  and 
 same  size);  (Between  Centre  (C)  and 
 Focus  (F)  -  Beyond  Centre  -  Real, 
 inverted,  and  larger);  (on  Focus  -  In?nity  - 
 Real,  inverted,  and  enlarged);  (On  Focal 
 length  (Between  Pole  and  Focus)  - 
 Behind  Mirror  -  Virtual,  straight  and 
 enlarged). 
 Q.13.  If  ‘u’  is  the  object-distance,  ‘v’  is  the 
 image-distance  and  ‘f’  is  the  focal  length 
 of  a  spherical  mirror  then  which  of  the 
 following  is  a  correct  expression  for  the 
 mirror formula? 
 SSC MTS 07/07/2022 (Morning) 
 (a) 1/v + 1/u = –1/f    (b) 1/v – 1/u = 1/f 
 (c) 1/v + 1/u = 1/f       (d) 1/v – 1/u = –1/f 
 Sol.13.(c)  1/v  +  1/u  =  1/f  .  There  are  two 
 types  of  spherical  mirrors  :  concave 
 mirrors  (If  the  re?ective  surface  is  on  the 
 side  curved  inwards)  and  convex  mirrors 
 (if the re?ective surface is curved 
 outwards). The  lens formula  is 1/v-1/u 
 = 1/f. 
 Q.14.  The  splitting  of  white  light  into  its 
 component colours is called ______. 
 SSC MTS 12/07/2022 (Morning) 
 (a) refraction  (b) re?ection 
 (c) scattering  (d) dispersion 
 Sol.14.(d)  Dispersion  .  Refraction  - 
 Redirection  of  a  wave  as  it  passes  from 
 one  medium  to  another.  Re?ection  - 
 When  a  ray  of  light  approaches  a  smooth 
 polished surface, it bounces back. 
 Q.15.  The  re?ection  on  a  bathroom 
 mirror,  the  lake,  and  the  glare  on  a  pair  of 
 glasses  are  caused  by  which  type  of 
 re?ection? 
 SSC CHSL 03/06/2022 (Evening) 
 (a) Multiple re?ection 
 (b) Specular re?ection 
 (c) Glossy re?ection 
 (d) Diffused re?ection 
 Sol.15.(b)  Specular  re?ection  is  de?ned 
 as  light  re?ected  from  a  smooth  surface 
 at  a  de?nite  angle  like  a  re?ection  on  a 
 bathroom  mirror.  Diffuse  re?ection  is 
 produced  by  rough  surfaces  that  tend  to 
 re?ect  light  in  all  directions  like  reading  a 
 newspaper.  Multiple  re?ections,  when 
 we  take  two  mirrors,  a  single  source  of 
 light  can  be  re?ected  multiple  times  like 
 in  a  barber's  shop,  we  see  the  back  of  the 
 head  using  multiple  re?ections  of  two 
 mirrors. 
 Q.16.  Which  of  the  following  elements  is 
 NOT  suitable  for  the  fabrication  of  a  light 
 emitting diode structure? 
 SSC CGL 12/04/2022 (Afternoon) 
 (a) Gallium phosphide 
 (b) Indium gallium nitride 
 (c) Germanium 
 (d) Gallium arsenide 
 Sol.16.(c)  Germanium  (Group  14,  Atomic 
 number  32)  -  It  is  a  semiconductor 
 (properties  between  the  metals  and  the 
 non-metals).  Uses  -  as  a  transistor,  used 
 in  wide-angle  camera  lenses  and 
 objective lenses for microscopes. 
 Q.17  .  Gold  and  copper  happen  to  absorb 
 ______and violet light, leaving yellow light. 
 SSC CGL 12/04/2022 (Evening) 
 (a) green  (b) blue   (c) red  (d) orange 
 Sol.17.(b)  Blue  .  So  gold  and  copper  are 
 yellowish  in  color.  Gold  (Au,  Group  11, 
 Atomic  number  79).  Silver  (Ag,  Group  11, 
 Atomic number 47). 
 Q.18.  The absolute refractive index of 
 ______ is 2.42. 
 SSC MTS 07/10/2021 (Evening) 
 (a) air  (b) diamond 
 (c) crown glass  (d) water 
 Sol.18.(b)  Diamond.  Refractive  index 
 measures  the  bending  of  a  ray  of  light 
 when  passing  from  one  medium  into 
 another.  The  refractive  index  of  a 
 substance  is  described  by  the  formula,  n 
 =  c/v,  where  c  is  the  speed  of  light  in 
 vacuum  (3  ×  10 
 8 
 m/s)  and  v  is  the  phase 
 velocity  of  light.  Refractive  Index  -  Air  - 
 1.0003,  Water  -  1.333,  Diamond  -  2.417, 
 Ice- 1.31, Ethyl Alcohol - 1.36, Vacuum- 1. 
 Q.19.  Apart  from  the  red  and  green 
 wavelengths  of  sunlight,  which  other 
 wavelength  of  sunlight  is  absorbed  by 
 water molecules in the ocean? 
 SSC MTS 08/10/2021 (Morning) 
 (a) Orange  (b) Blue  (c) Violet  (d) Yellow 
 Sol.19.(d)  Yellow  .  When  sunlight  hits  the 
 ocean,  some  of  the  light  is  re?ected  back 
 directly  but  most  of  it  penetrates  the 
 ocean  surface  and  interacts  with  the 
 water molecules. 
 Q.20.  Which  of  the  following  types  of 
 mirrors show a lateral inversion of light? 
 SSC MTS 13/10/2021 (Afternoon) 
 (a) Convex mirror        (b) Concave mirror 
 (c) Rectangle mirror   (d) Plane mirror 
 Sol.20.(d)  Plane  mirror  .  Lateral  inversion 
 is  the  reversal  of  a  mirror  image  where 
 the  right  side  of  the  object  appears  on 
 the  left  side  behind  the  mirror. 
 Characteristics  of  a  plane  mirror  -  Image 
 are  Virtual  and  Erect.  Image  is  formed 
 behind  the  mirror.  Size  of  the  image  is 
 equal.  Distance  of  image  and  mirror  is 
 equal  to  the  distance  of  object  and 
 mirror. 
 Q.21.  The  color  of  the  clear  sky  is  blue 
 due to the phenomenon of: 
 SSC MTS 18/10/2021 (Morning) 
 (a) dispersion of light (b) re?ection of light 
 (c) scattering of light  (d) refraction of light 
 Sol.21.(c)  Scattering  of  light  .  CV  Raman 
 was  awarded  the  Nobel  prize  in  Physics 
 in  1930  for  his  discovery  of  Raman  effect 
 (Scattering  of  light).  The  Tyndall  effect  is 
 the  phenomenon  of  the  scattering  of 
 light by colloidal particles. 
 Q.22.  What is the full form of LED? 
 SSC MTS 27/10/2021 (Morning) 
 (a) Linear Emergency Device 
 (b) Light Emitting Diode 
 (c) Liquid Emitting Display 
 (d) Light Emitting Device 
 Sol.22.(b)  Light-emitting Diode  (LED) -  A 
 semiconductor device, which can emit 
 light when an electric current passes 
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 through  it.  Working  principle  - 
 Electroluminescence. 
 Q.23.  Which  phenomenon  deals  with  the 
 scattering  of  light  by  molecules  of  a 
 medium  when  they  are  excited  to 
 vibrational energy levels? 
 SSC CGL 24/08/2021 (Evening) 
 (a) Huygens Effect   (b) Maxwell Effect 
 (c) Raman Effect      (d) Rayleigh Effect 
 Sol.23.(c)  Raman  Effect.  Huygens' 
 principle  states  that  every  point  on  a 
 wavefront  may  be  considered  as  a 
 source  of  secondary  waves.  Maxwell 
 Effect  is  a  phenomenon  of 
 electromagnetic  induction  in  which  an 
 electric  charge,  near  a  solenoid  in  which 
 current  changes  slowly,  feels  an 
 electromotive  force  (e.m.f.)  even  if  the 
 magnetic  ?eld  is  practically  static  inside 
 and  null  outside.  Rayleigh  Effect  is  a 
 phenomenon  of  scattering  of  light  or 
 other  electromagnetic  radiation  by 
 particles  much  smaller  than  the 
 wavelength of the radiation. 
 Q.24.  The  phenomenon  of  deviation  of 
 light  rays  from  their  original  path,  when 
 they  pass  from  one  medium  to  another, 
 is called ____. 
 SSC CPO 25/11/2020 (Evening) 
 (a) obstruction  (b) re?ection 
 (c) Diffraction  (d) Refraction 
 Sol.24.(d)  Refraction.  When  light  moves 
 from  rarer  (air)  to  a  denser  medium 
 (water),  it  bends  towards  the  normal  and 
 if  it  moves  from  a  denser  to  a  rarer 
 medium, it bends away from the normal. 
 Q.25.  What  is  the  name  of  the 
 phenomena  (derived  by  scattering  of  the 
 light)  in  which  mountain  tops  acquire  a 
 rosy  or  orange  hue  around  sunrise  and 
 sunset ? 
 SSC CGL 04/03/2020 (Evening) 
 (a) Brillouin scattering 
 (b) Circle of confusion 
 (c) Alpenglow 
 (d) Barrel distortion 
 Sol.25.(c)  Alpenglow  .  It  is  either  the 
 indirect  sunlight  re?ection  off  of  clouds 
 after  sunset  or  before  sunrise,  or  to 
 direct  sunlight  that  occurs  near  sunset  or 
 sunrise. 
 Q.26.  The  total  number  of  images 
 formed  by  two  mirrors  inclined  at  120°  to 
 each other is ______. 
 SSC CGL 05/03/2020 (Afternoon) 
 (a) 1  (b) 2  (c) 4  (d) 3 
 Sol.26.(b) 2.  The number of images 
 formed when  two mirrors  are placed at 
 an  angle  theta  (  )  to  each  other  is  given ?
 by :  n = (360° /  ) - 1 ?
 So,  here,  we  have  the  mirrors  placed  at 
 an angle  = 120° ?
 n = no. of images formed ?
 n = ( 360° /120° ) - 1 ?
 n = 3 - 1  n = 2 ? ?
 So, a total of two images will be formed. 
 Heat and Thermodynamics 
 Q.27  .  Which  of  the  following  best 
 describes the process of calorimetry? 
 SSC MTS 14/09/2023 (3rd Shift) 
 (a) Measuring the amount of 
 compressive strength 
 (b) Measuring the amount of force 
 (c) Measuring the amount of electricity 
 (d) Measuring the amount of heat energy 
 transferred 
 Sol.27.(d)  Calorimetry  is  the  process  of 
 measuring  the  amount  of  heat  released 
 or  absorbed  during  a  chemical  reaction. 
 By  knowing  the  change  in  heat,  it  can  be 
 determined  whether  or  not  a  reaction  is 
 exothermic  (releases  heat)  or 
 endothermic  (absorbs  heat).  Calorimetry 
 also  plays  a  large  part  of  everyday  life, 
 controlling  the  metabolic  rates  in 
 humans  and  consequently  maintaining 
 such functions like body temperature. 
 Q.28.  In  which  method  of  cooking  is  food 
 heated  slowly  over  a  source  of  heat  and 
 cooked  by  high  heat  and  air  convection 
 depending  on  the  position  of  the  food  in 
 relation to the ?re? 
 SSC CGL 26/07/2023 (2nd shift) 
 (a) Spit-roasting  (b) Braising 
 (c) Poaching  (d) Stewing 
 Sol.28.(a)  Spit-roasting.  Braising  -  The 
 cooking  of  meat  or  vegetables  by  heating 
 them  slowly  with  oil  and  moisture  in  a 
 tightly  sealed  vessel.  Poaching  -  A  moist 
 heat  method  of  cooking  by  submerging 
 food  in  some  kind  of  liquid  and  heating 
 at  a  low  temperature.  Stewing  -  A 
 combination  cooking  method  that  uses 
 small,  uniform  pieces  of  meat  that  are 
 totally  immersed  in  liquid  and  slowly 
 simmered. 
 Q.29.  Who coined the term 'zeroth law of 
 thermodynamics'  in  1931,  which  asserts 
 that  two  bodies  in  equilibrium  with  a  third 
 are in equilibrium with each other? 
 SSC CGL 27/07/2023 (3rd shift) 
 (a) James Clerk Maxwell 
 (b) Max Planck 
 (c) Josiah Willard Gibbs 
 (d) Ralph H. Fowler 
 Sol.29.(d) Ralph H Fowler. 
 Thermodynamics  deals  with  the  relations 
 between  heat  and  other  forms  of  energy. 
 James  Clerk  Maxwell  -  Theory  of 
 electromagnetism.  Max  Planck  -  The 
 quantum  of  action  (Planck's  constant). 
 Josiah  Willard  Gibbs  -  Gibbs  energy 
 (Available energy in a system). 
 Q.30.  Triple point can be de?ned as: 
 Matric Level 28/06/2023 (Shift - 1) 
 (a) the condition of temperature under 
 which the gaseous and liquid phases 
 of a substance can exist in 
 equilibrium 
 (b) the temperature at which solid is 
 converted into liquid 
 (c) the condition of pressure under which 
 the solid and liquid phases of a 
 substance can exist in equilibrium 
 (d) the condition of temperature and 
 pressure under which the gaseous, 
 liquid and solid phases of a 
 substance can exist in equilibrium 
 Sol.30.(d)  The  triple  point  of  water  is  at 
 273.16  kelvin  (0.01  °C  or  32.02  °F)  and  a 
 pressure of 611.7 Pascals. 
 Q.31.  According  to  law,  heat 
 produced  by  an  electric  current  is  directly 
 proportional  to  the  resistance  of  the 
 conductor,  the  square  of  the  current,  and 
 the time for which it ?ows. 
 SSC MTS 17/05/2023 (Afternoon) 
 (a) Hooke's  (b) Charles's 
 (c) Faraday's  (d) Joule's 
 Sol.31.(d)  Joule's.  Joule's  law  of  heating, 
 H  =  I 
 2 
 RT,  where,  H  -  Heat,  I  -  Current,  R  - 
 Resistance,  T  -  time.  Hooke's  law  (law  of 
 elasticity)  -  Discovered  by  the  English 
 scientist  Robert  Hooke  in  1660,  which 
 states  that,  for  relatively  small 
 deformations  of  an  object,  the 
 displacement  or  size  of  the  deformation 
 is  directly  proportional  to  the  deforming 
 force  or  load.  Faraday's  law  -  The 
 magnitude  of  induced  emf  is  equal  to  the 
 rate  of  change  of  ?ux  linkages  with  the 
 coil. 
 Q.32.  Tensile  or  compressive  stress  can 
 also be termed as _______. 
 SSC MTS 13/06/2023 (Morning) 
 (a) longitudinal stress 
 (b) tangential stress 
 (c) hydraulic stress 
 (d) shearing stress 
 Sol.32.(a)  Longitudinal  stress  (axial 
 stress)  .  Other  types  of  stress  :  Tangential 
 stress  is  a  type  of  stress  that  acts 
 perpendicular  to  the  surface  of  an  object. 
 Hydraulic  stress  is  a  type  of  stress  that  is 
 caused  by  the  pressure  of  a  ?uid. 
 Shearing stress is a type of stress that 
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 acts parallel to the surface of an object. 
 Q.33.  In  which  of  the  following  ways  of 
 heat transfer no medium is required? 
 SSC CHSL 09/03/2023 (3rd Shift) 
 (a) Radiation and Conduction both 
 (b) Conduction 
 (c) Convection 
 (d) Radiation 
 Sol.33.(d)  Radiation  :  Energy  that  comes 
 from  a  source  and  travels  through  space 
 at  the  speed  of  light.  It  has  wave-like 
 properties  and  can  be  called 
 “electromagnetic  waves”.  Convection  : 
 Process  of  heat  transfer  by  the 
 movement  of  molecules  within  ?uids 
 such  as  gasses  and  liquids.  Conduction  : 
 Process  by  which  heat  energy  is 
 transmitted  through  collisions  between 
 neighbouring atoms or molecules. 
 Q.34.  ______  is  de?ned  as  the 
 temperature  to  which  the  air  would  have 
 to  cool  (at  constant  pressure  and 
 constant  water  vapour  content)  in  order 
 to reach saturation. 
 SSC CGL 13/04/2022 (Afternoon) 
 (a) Dew point temperature 
 (b) Air temperature 
 (c) Relative humidity 
 (d) Surface temperature 
 Sol.34.(a)  Dew  point  temperature.  It  is 
 the  temperature  the  air  needs  to  be 
 cooled  to  (at  constant  pressure)  in  order 
 to achieve a relative humidity of 100%. 
 Q.35.  What  is  the  Steam  Point  on  the 
 Fahrenheit scale? 
 SSC MTS 13/10/2021 (Morning) 
 (a) 32 
 ° 
 F  (b) 100 
 ° 
 F   (c) 212 
 ° 
 F   (d) 80 
 ° 
 F 
 Sol.35.(c)  212 
 ° 
 F .  Steam  point  is  the 
 temperature  at  which  the  maximum 
 vapour  pressure  of  water  is  equal  to  one 
 atmosphere.  It  has  a  value  of  100°C  on 
 the Celsius scale. 
 Q.36.  Heat,  in  ______,  is  a  type  of  energy 
 transfer  from  a  warmer  substance  to  a 
 colder one. 
 SSC CHSL 06/08/2021 (Morning) 
 (a) gravity  (b) friction 
 (c) thermodynamics        (d) magnet 
 Sol.36.(c)  Thermodynamics  .  During 
 energy  transfer,  the  energy  moves  from 
 the  hotter  object  to  the  colder  object. 
 This  means  that  the  hotter  object  will 
 cool  down  and  the  colder  object  will 
 warm  up.  The  energy  transfer  will 
 continue  until  both  objects  are  at  the 
 same temperature. Heat is measured in 
 joules (J). 
 Q.37.  _______  expansion  makes  the  Eiffel 
 Tower taller during summers. 
 SSC CGL 04/03/2020 (Morning) 
 (a) thermal  (b) slope 
 (c) gravitational  (d) chemical 
 Sol.37.(a)  Thermal  expansion  is  a 
 phenomenon  due  to  which  the  metal 
 expands  when  heated  and  contracts 
 when  cooled.  The  Eiffel  Tower  gets  taller 
 by up to  6 inches during the summer. 
 Fluid Mechanics 
 Q.38.  In  1851,  who  founded  the  science 
 of  hydrodynamics  with  his  law  of 
 viscosity  describing  the  velocity  of  a 
 small sphere through a viscous ?uid? 
 SSC CHSL 09/08/2023 (4th shift) 
 (a) Daniel Bernoulli 
 (b) George Gabriel Stokes 
 (c) Evangelista Torricelli 
 (d) Heinrich Gustav Magnus 
 Sol.38.(b)  George  Gabriel  Stokes.  Daniel 
 Bernoulli  -  Known  for  Bernoulli's 
 principle.  According  to  this  principle,  an 
 increase  in  the  speed  of  a  ?uid  occurs 
 simultaneously  with  a  decrease  in 
 pressure  or  a  decrease  in  the  ?uid's 
 potential  energy.  Evangelista  Torricelli  - 
 Known  for  his  invention  of  the  barometer, 
 a  device  used  to  measure  atmospheric 
 pressure.  Heinrich  Gustav  Magnus  - 
 Known  for  Magnus  effect,  an  observable 
 phenomenon  that  is  commonly 
 associated  with  a  spinning  object 
 moving through the air or a ?uid. 
 Q.39.  Whose  law  states  that  total  energy 
 per  unit  mass  of  ?owing  ?uid,  at  any 
 point  in  the  subsurface,  is  the  sum  of  the 
 kinetic,  potential,  and  ?uid-pressure 
 energy and is equal to a constant value? 
 SSC CGL 19/07/2023 (3rd shift) 
 (a) Daniel Bernoulli 
 (b) Evangelista Torricelli 
 (c) Blaise Pascal 
 (d) Marie Poiseuille 
 Sol.39.(a)  Daniel  Bernoulli.  Torricelli's 
 law  -  The  parting  speed  of  a  jet  of  water, 
 based  on  the  distance  below  the  surface 
 at  which  the  jet  starts,  assuming  no  air 
 resistance,  viscosity,  or  other  hindrance 
 to  the  ?uid  ?ow.  Pascal's  law  -  The 
 pressure  applied  to  an  enclosed  ?uid  will 
 be  transmitted  without  a  change  in 
 magnitude  to  every  point  of  the  ?uid  and 
 the  walls  of  the  container.  Poiseuille's 
 law  -  It  gives  the  pressure  drop  in  an 
 incompressible  and  Newtonian  ?uid  in 
 laminar  ?ow  ?owing  through  a  long 
 cylindrical pipe of a constant 
 cross-section. 
 Q.40.  _______  forces  water  through  a 
 semipermeable  membrane  and  removes 
 contaminants. 
 SSC CHSL 16/03/2023 (4th Shift) 
 (a) Boiling  (b) Distillation 
 (c) Reverse Osmosis        (d) Filtration 
 Sol.40.(c)  Reverse  Osmosis  .  Filtration  is 
 the  process  in  which  solid  particles  in  a 
 liquid  or  gaseous  ?uid  are  removed. 
 Boiling  is  the  process  by  which  a  liquid 
 turns  into  a  vapor  when  it  is  heated  to  its 
 boiling  point.  Distillation  is  a  process 
 involving  the  conversion  of  a  liquid  into 
 vapor  that  is  subsequently  condensed 
 back to liquid form. 
 Q.41.  What is the relative density of silver 
 SSC CHSL 19/03/2020 (Evening) 
 (a) 9.5  (b) 7.2  (c) 10.4  (d) 10.8 
 Sol.41.(d)  10.8.  Relative  density  is  a 
 comparative  measure  of  the  density  of  a 
 substance  to  the  density  of  a  reference 
 substance (Usually Water). 
 Electric Current and Its Effects 
 Q.42.  The  neutral  point  in  the  magnetic 
 ?eld  of  a  horizontally  positioned  bar 
 magnet is the : 
 SSC CHSL 02/08/2023 (2nd shift) 
 (a) point where the magnetic ?eld 
 changes direction 
 (b) point where the magnetic ?eld is the 
 weakest 
 (c) point where the magnetic ?eld is the 
 strongest 
 (d) point where the magnetic ?eld is zero 
 Sol.42.(d)  Neutral  point  :  The  point  at 
 which  the  resultant  magnetic  ?eld  is 
 zero.  It  is  a  point  where  the  magnetic 
 ?eld  produced  due  to  a  bar  magnet  is 
 completely  balanced  by  the  horizontal 
 component  of  Earth's  magnetic  ?eld. 
 Magnetic  Field  -  The  region  around  a 
 magnetic  material  or  a  moving  electric 
 charge  within  which  the  force  of 
 magnetism  acts.  Types  of  magnets  : 
 Permanent  magnet,  temporary  magnet 
 and electromagnet. 
 Q.43.  In  1834,  who  proposed  a  law  that 
 states  that  the  current  induced  by  a 
 change  in  ?ow  opposes  the  effect 
 producing the change ? 
 SSC CHSL 02/08/2023 (4th shift) 
 (a) David Brewster 
 (b) Henry Moseley 
 (c) Christian Johann Doppler 
 (d) Heinrich Friedrich Lenz 
 Sol.43.(d)  Heinrich  Friedrich  Lenz. 
 Lenz’s  law  -  An  induced  electric  current 
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Page 5


 Pinnacle  Physics 
 Physics 
 Light and Optics 
 Q.1.  A  concave  spherical  mirror  has  a 
 radius  of  curvature  of  30  cm.  An  object 
 was  placed  15  cm  away  from  the  pole  in 
 front  of  the  mirror  on  the  principal  axis. 
 Choose  the  correct  option  for  the 
 position,  size  and  nature  of  the  image 
 formed, respectively. 
 SSC Stenographer 13/10/2023 (Morning) 
 (a) Behind the mirror, enlarged, virtual 
 and erect 
 (b) At in?nity, highly enlarged, real and 
 inverted 
 (c) Between Focus and Centre, 
 diminished, real and inverted 
 (d) At the focus, highly diminished 
 point-sized, real and inverted 
 Sol.1.(b)  At  In?nity,  highly  enlarged,  real 
 and  inverted.  We  know  that,  focus  of  a 
 mirror,  f  =  R/2,  where  R  is  the  radius  of 
 curvature  of  the  mirror.  Here  in  this  case, 
 f  =  -  30/2  =  -15  cm.  Also,  distance  of  the 
 object  from  the  mirror,  u  =  -15  cm.  It 
 means  that  the  object  is  placed  at  the 
 focus  of  the  mirror.  Now  it  is  clear  that 
 when  the  object  is  placed  at  focus  of  the 
 mirror,  the  respective  image  will  be 
 formed  at  in?nity.  The  size  of  the  image 
 would  be  highly  enlarged.  The  nature  of 
 the image would be real and inverted. 
 Q.2.  In  optics,  which  term  refers  to  the 
 opening  of  the  diaphragm  of  a  lens  that 
 spatially limits the propagation of light ? 
 SSC MTS 13/09/2023 (1st Shift) 
 (a) Collimator  (b) Aperture 
 (c) Apostilb  (d) Meniscus 
 Sol.2.(b)  Aperture.  Collimator  -  A  device 
 which  narrows  a  beam  of  particles  or 
 waves.  Apostilb  -  An  obsolete  unit  of 
 luminance.  Meniscus  -  A  C-shaped  piece 
 of  tough,  rubbery  cartilage  that  acts  as  a 
 shock  absorber  between  the  shinbone 
 and the thigh bone. 
 Q.3.  White light is an example of: 
 SSC CHSL 04/08/2023 (2nd shift) 
 (a) laser light 
 (b) plane polarized light 
 (c) monochromatic light 
 (d) polychromatic light 
 Sol.3.(d)  Polychromatic  light  -  The  light 
 consists  of  a  broad  range  of 
 wavelengths.  Examples  -  Mercury  Light, 
 Sunlight,  laser-pumped  plasma  light. 
 Monochromatic  light  -  The  light  consists 
 of  only  one  speci?c  wavelength. 
 Examples  -  laser  beam,  Sodium  lamps, 
 Spark  lamps.  Plane  polarized  light  -  It 
 consists  of  waves  in  which  the  direction 
 of  vibration  is  the  same  for  all  waves. 
 Examples  -  laser  lights  and  devices. 
 Laser  light  -  Laser  (Light  Ampli?cation  by 
 Stimulated  Emission  of  Radiation)  is  an 
 arti?cial  source  of  light  radiation  that 
 emits  a  coherent  beam  of  photons,  as 
 the  source  is  stable  in  frequency, 
 wavelength, and power. 
 Q.4.  Which  telescope  was  invented  by 
 Isaac  Newton  in  the  17th  century  by 
 using  a  concave  mirror  to  collect  light 
 instead  of  a  simple  lens  which  produces 
 false  colors  due  to  the  dispersion  of 
 light? 
 SSC CHSL 09/08/2023 (3rd shift) 
 (a) Re?ecting telescope 
 (b) Infrared telescope 
 (c) Monocular telescope 
 (d) Graphic telescope 
 Sol.4.(a)  Re?ecting  telescope  -  Uses 
 mirrors  which  cause  light  to  re?ect  at 
 different  angles  within  the  optical  tube 
 and  extends  the  overall  light  path.  Two 
 major  types  of  telescopes  :  Re?ecting 
 Telescopes  and  Refracting  Telescopes 
 (used  lenses  to  magnify  objects). 
 Infrared  telescope  :  Uses  infrared  light  to 
 detect celestial bodies. 
 Q.5.  The  minimum  distance  of  distinct 
 vision  for  a  young  adult  person  with  no 
 defect in eyes is: 
 SSC CHSL 11/08/2023 (4th shift) 
 (a) 20 m  (b) 25 cm  (c) 20 cm  (d) 25 m 
 Sol.5.(b)  25  cm.  For  a  normal  eye,  the  far 
 point  is  at  in?nity  and  the  near  point  of 
 distinct  vision  is  about  25  cm  in  front  of 
 the  eye.  Hypermetropia  (far-sightedness) 
 :  When  the  point  goes  farther  from  25 
 cm.  Lens  used  :  Convex.  Myopia 
 (Nearsightedness):  Near  objects  appear 
 clear,  but  objects  farther  away  look 
 blurry. Lens used: Concave. 
 Q.6.  Which  colour  of  light  from  VIBGYOR 
 has minimum energy ? 
 SSC CHSL 14/08/2023 (1st shift) 
 (a) Green (b) Violet (c) Yellow (d) Red 
 Sol.6.(d)  Red  .  It  has  the  longest 
 wavelength  and  least  energy  of  the 
 visible  colors  of  light.  Wavelength  -  The 
 distance  between  two  successive  crests 
 or  troughs.  Violet  has  the  shortest 
 wavelength.  Frequency  -  It  refers  to  the 
 number  of  waves  passing  through  a 
 point  per  second.  Violet  has  the  highest 
 frequency.  The  white  light  consists  of  7 
 colors  VIBGYOR  (Violet  -  Indigo  -  Blue  - 
 Green - Yellow - Orange - Red). 
 Q.7.  Why  can  you  not  see  objects  in  a 
 dim  lit  room  when  you  come  from  a 
 brightly lit room? 
 SSC CGL 25/07/2023 (4th shift) 
 (a) The iris dilates the eye lens to allow 
 less light to enter the eye. 
 (b) The iris contracts the pupil to allow 
 less light to enter the eye. 
 (c) The vitreous humour dilates the pupil 
 to allow less light to enter the eye. 
 (d) The cornea contracts the pupil to 
 allow less light to enter the eye. 
 Sol.7.(b)  Iris  -  It  gives  a  distinct  color  to 
 the  eyes.  The  eyeball  is  spherical  in 
 shape  having  a  diameter  of  23  mm. 
 Vitreous  humor  present  in  between  lens 
 and  retina.  Retina  contains  three  layers 
 of  neural  cells  (ganglion  cells,  bipolar 
 cells,  photoreceptor  cells).  Cornea  -  The 
 front  most  and  transparent  covering  of 
 the  eye.  Light  enters  the  human  eye 
 through the cornea. 
 Q.8.  What  will  be  the  focal  length  of  a 
 convex  lens  with  the  power  of  a  +2.5 
 Diopter? 
 Higher Secondary 28/06/2023 ( Shift - 2) 
 (a) 20 cm (b) 10 cm (c) 40 cm (d) 5 cm 
 Sol.8.(c) 40 cm.  Using the formula: 
 focal  length  (f)  of  convex  Lens  =  1/Power 
 (P) 
 Given,  the power (P) =  +2.5 diopters 
 then  focal  length:  f  =  1  /  2.5  =  0.4  meters 
 =  40  centimeters  .  Focal  length  of  convex 
 lens  is  always  positive  and  concave  lens 
 is always negative. 
 Q.9.  Raman  wants  to  use  a  rear-view 
 mirror  in  his  vehicle.  Which  type  of 
 mirror should he pick for it ? 
 SSC CHSL 10/03/2023 (2nd Shift) 
 (a) Convex Mirrors       (b) Plane Mirrors 
 (c) Cylindrical Mirrors  (d) Concave Mirrors 
 Sol.9.(a)  Convex  Mirrors.  This  is 
 because  they  give  an  erect,  virtual,  full 
 size  diminished  image  of  distant  objects 
 with  a  wider  ?eld  of  view.  Uses  - 
 Sunglasses, street lights. 
 Q.10.  An  image  formed  by  the  convex 
 mirror is always _________. 
 SSC CHSL 14/03/2023 (3rd Shift) 
 (a) virtual and inverted (b) real and erect 
 (c) virtual and erect      (d) real and inverted 
 Sol.10.(c)  Virtual  and  erect.  Convex 
 mirror  (Diverging  Mirror)  -  It  has  a 
 re?ecting  surface  that  bulges  outwards, 
 and  away  from  the  centre  of  curvature. 
 Uses  -  Rear  view  mirrors,  Street  light 
 re?ector, etc. 
 Q.11.  Which of the following statements 
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 Pinnacle  Physics 
 regarding the lenses is/are correct? 
 I. Power of a convex lens is represented 
 as a positive number. 
 II. Power of a concave lens is 
 represented as a negative number. 
 SSC CHSL 17/03/2023 (4th Shift) 
 (a) Both I and II  (b) Only II 
 (c) Only I  (d) Neither I nor II 
 Sol.11.(a)  Both  I  and  II.  The  focal  length  of 
 the  convex  lens  is  always  positive.  The 
 power  of  the  lens  = 
 .  If  the  focal  length 
 1 
 ??????????     ??????????h ( ????     ?????????? )
 is  positive,  then  power  is  always  positive. 
 Uses  of  convex  lens  -  Magnifying  glasses, 
 Eyeglasses, Cameras, Microscopes etc. 
 A  concave  lens  (diverging  lens)  diverges 
 the  rays  incident  on  it.  Its  power  is 
 negative.  Uses  of  concave  lenses  - 
 telescopes, lasers etc. 
 Q.12.  Which  of  the  following  pair  of 
 position  of  object  –  position  of  image  – 
 size  of  image,  is  NOT  correct  for  concave 
 mirror? 
 SSC CPO 10/11/2022 (Morning) 
 (a) At F - At in?nity - Highly enlarged 
 (b) Between C and F - Beyond C - 
 Enlarged 
 (c) Beyond C - Between F and C - 
 Diminished 
 (d) At in?nity - At C - Highly diminished 
 Sol.12.(d)  At  in?nity  -  At  C  -  Highly 
 diminished.  Spherical  mirrors  are  of  two 
 types,  concave  and  convex.  Image 
 formation  by  Concave  Mirror  (Object 
 Position  -  Image  Position  -  Image  Nature 
 and  Size)  :  (At  In?nity  -  At  F  -  Real,  point 
 size);  (Beyond  Center  C  -  Between  C  and 
 F  (Focus)  -  Diminished,  Real  and 
 Inverted);  (On  Centre  -  Real,  inverted,  and 
 same  size);  (Between  Centre  (C)  and 
 Focus  (F)  -  Beyond  Centre  -  Real, 
 inverted,  and  larger);  (on  Focus  -  In?nity  - 
 Real,  inverted,  and  enlarged);  (On  Focal 
 length  (Between  Pole  and  Focus)  - 
 Behind  Mirror  -  Virtual,  straight  and 
 enlarged). 
 Q.13.  If  ‘u’  is  the  object-distance,  ‘v’  is  the 
 image-distance  and  ‘f’  is  the  focal  length 
 of  a  spherical  mirror  then  which  of  the 
 following  is  a  correct  expression  for  the 
 mirror formula? 
 SSC MTS 07/07/2022 (Morning) 
 (a) 1/v + 1/u = –1/f    (b) 1/v – 1/u = 1/f 
 (c) 1/v + 1/u = 1/f       (d) 1/v – 1/u = –1/f 
 Sol.13.(c)  1/v  +  1/u  =  1/f  .  There  are  two 
 types  of  spherical  mirrors  :  concave 
 mirrors  (If  the  re?ective  surface  is  on  the 
 side  curved  inwards)  and  convex  mirrors 
 (if the re?ective surface is curved 
 outwards). The  lens formula  is 1/v-1/u 
 = 1/f. 
 Q.14.  The  splitting  of  white  light  into  its 
 component colours is called ______. 
 SSC MTS 12/07/2022 (Morning) 
 (a) refraction  (b) re?ection 
 (c) scattering  (d) dispersion 
 Sol.14.(d)  Dispersion  .  Refraction  - 
 Redirection  of  a  wave  as  it  passes  from 
 one  medium  to  another.  Re?ection  - 
 When  a  ray  of  light  approaches  a  smooth 
 polished surface, it bounces back. 
 Q.15.  The  re?ection  on  a  bathroom 
 mirror,  the  lake,  and  the  glare  on  a  pair  of 
 glasses  are  caused  by  which  type  of 
 re?ection? 
 SSC CHSL 03/06/2022 (Evening) 
 (a) Multiple re?ection 
 (b) Specular re?ection 
 (c) Glossy re?ection 
 (d) Diffused re?ection 
 Sol.15.(b)  Specular  re?ection  is  de?ned 
 as  light  re?ected  from  a  smooth  surface 
 at  a  de?nite  angle  like  a  re?ection  on  a 
 bathroom  mirror.  Diffuse  re?ection  is 
 produced  by  rough  surfaces  that  tend  to 
 re?ect  light  in  all  directions  like  reading  a 
 newspaper.  Multiple  re?ections,  when 
 we  take  two  mirrors,  a  single  source  of 
 light  can  be  re?ected  multiple  times  like 
 in  a  barber's  shop,  we  see  the  back  of  the 
 head  using  multiple  re?ections  of  two 
 mirrors. 
 Q.16.  Which  of  the  following  elements  is 
 NOT  suitable  for  the  fabrication  of  a  light 
 emitting diode structure? 
 SSC CGL 12/04/2022 (Afternoon) 
 (a) Gallium phosphide 
 (b) Indium gallium nitride 
 (c) Germanium 
 (d) Gallium arsenide 
 Sol.16.(c)  Germanium  (Group  14,  Atomic 
 number  32)  -  It  is  a  semiconductor 
 (properties  between  the  metals  and  the 
 non-metals).  Uses  -  as  a  transistor,  used 
 in  wide-angle  camera  lenses  and 
 objective lenses for microscopes. 
 Q.17  .  Gold  and  copper  happen  to  absorb 
 ______and violet light, leaving yellow light. 
 SSC CGL 12/04/2022 (Evening) 
 (a) green  (b) blue   (c) red  (d) orange 
 Sol.17.(b)  Blue  .  So  gold  and  copper  are 
 yellowish  in  color.  Gold  (Au,  Group  11, 
 Atomic  number  79).  Silver  (Ag,  Group  11, 
 Atomic number 47). 
 Q.18.  The absolute refractive index of 
 ______ is 2.42. 
 SSC MTS 07/10/2021 (Evening) 
 (a) air  (b) diamond 
 (c) crown glass  (d) water 
 Sol.18.(b)  Diamond.  Refractive  index 
 measures  the  bending  of  a  ray  of  light 
 when  passing  from  one  medium  into 
 another.  The  refractive  index  of  a 
 substance  is  described  by  the  formula,  n 
 =  c/v,  where  c  is  the  speed  of  light  in 
 vacuum  (3  ×  10 
 8 
 m/s)  and  v  is  the  phase 
 velocity  of  light.  Refractive  Index  -  Air  - 
 1.0003,  Water  -  1.333,  Diamond  -  2.417, 
 Ice- 1.31, Ethyl Alcohol - 1.36, Vacuum- 1. 
 Q.19.  Apart  from  the  red  and  green 
 wavelengths  of  sunlight,  which  other 
 wavelength  of  sunlight  is  absorbed  by 
 water molecules in the ocean? 
 SSC MTS 08/10/2021 (Morning) 
 (a) Orange  (b) Blue  (c) Violet  (d) Yellow 
 Sol.19.(d)  Yellow  .  When  sunlight  hits  the 
 ocean,  some  of  the  light  is  re?ected  back 
 directly  but  most  of  it  penetrates  the 
 ocean  surface  and  interacts  with  the 
 water molecules. 
 Q.20.  Which  of  the  following  types  of 
 mirrors show a lateral inversion of light? 
 SSC MTS 13/10/2021 (Afternoon) 
 (a) Convex mirror        (b) Concave mirror 
 (c) Rectangle mirror   (d) Plane mirror 
 Sol.20.(d)  Plane  mirror  .  Lateral  inversion 
 is  the  reversal  of  a  mirror  image  where 
 the  right  side  of  the  object  appears  on 
 the  left  side  behind  the  mirror. 
 Characteristics  of  a  plane  mirror  -  Image 
 are  Virtual  and  Erect.  Image  is  formed 
 behind  the  mirror.  Size  of  the  image  is 
 equal.  Distance  of  image  and  mirror  is 
 equal  to  the  distance  of  object  and 
 mirror. 
 Q.21.  The  color  of  the  clear  sky  is  blue 
 due to the phenomenon of: 
 SSC MTS 18/10/2021 (Morning) 
 (a) dispersion of light (b) re?ection of light 
 (c) scattering of light  (d) refraction of light 
 Sol.21.(c)  Scattering  of  light  .  CV  Raman 
 was  awarded  the  Nobel  prize  in  Physics 
 in  1930  for  his  discovery  of  Raman  effect 
 (Scattering  of  light).  The  Tyndall  effect  is 
 the  phenomenon  of  the  scattering  of 
 light by colloidal particles. 
 Q.22.  What is the full form of LED? 
 SSC MTS 27/10/2021 (Morning) 
 (a) Linear Emergency Device 
 (b) Light Emitting Diode 
 (c) Liquid Emitting Display 
 (d) Light Emitting Device 
 Sol.22.(b)  Light-emitting Diode  (LED) -  A 
 semiconductor device, which can emit 
 light when an electric current passes 
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 Pinnacle  Physics 
 through  it.  Working  principle  - 
 Electroluminescence. 
 Q.23.  Which  phenomenon  deals  with  the 
 scattering  of  light  by  molecules  of  a 
 medium  when  they  are  excited  to 
 vibrational energy levels? 
 SSC CGL 24/08/2021 (Evening) 
 (a) Huygens Effect   (b) Maxwell Effect 
 (c) Raman Effect      (d) Rayleigh Effect 
 Sol.23.(c)  Raman  Effect.  Huygens' 
 principle  states  that  every  point  on  a 
 wavefront  may  be  considered  as  a 
 source  of  secondary  waves.  Maxwell 
 Effect  is  a  phenomenon  of 
 electromagnetic  induction  in  which  an 
 electric  charge,  near  a  solenoid  in  which 
 current  changes  slowly,  feels  an 
 electromotive  force  (e.m.f.)  even  if  the 
 magnetic  ?eld  is  practically  static  inside 
 and  null  outside.  Rayleigh  Effect  is  a 
 phenomenon  of  scattering  of  light  or 
 other  electromagnetic  radiation  by 
 particles  much  smaller  than  the 
 wavelength of the radiation. 
 Q.24.  The  phenomenon  of  deviation  of 
 light  rays  from  their  original  path,  when 
 they  pass  from  one  medium  to  another, 
 is called ____. 
 SSC CPO 25/11/2020 (Evening) 
 (a) obstruction  (b) re?ection 
 (c) Diffraction  (d) Refraction 
 Sol.24.(d)  Refraction.  When  light  moves 
 from  rarer  (air)  to  a  denser  medium 
 (water),  it  bends  towards  the  normal  and 
 if  it  moves  from  a  denser  to  a  rarer 
 medium, it bends away from the normal. 
 Q.25.  What  is  the  name  of  the 
 phenomena  (derived  by  scattering  of  the 
 light)  in  which  mountain  tops  acquire  a 
 rosy  or  orange  hue  around  sunrise  and 
 sunset ? 
 SSC CGL 04/03/2020 (Evening) 
 (a) Brillouin scattering 
 (b) Circle of confusion 
 (c) Alpenglow 
 (d) Barrel distortion 
 Sol.25.(c)  Alpenglow  .  It  is  either  the 
 indirect  sunlight  re?ection  off  of  clouds 
 after  sunset  or  before  sunrise,  or  to 
 direct  sunlight  that  occurs  near  sunset  or 
 sunrise. 
 Q.26.  The  total  number  of  images 
 formed  by  two  mirrors  inclined  at  120°  to 
 each other is ______. 
 SSC CGL 05/03/2020 (Afternoon) 
 (a) 1  (b) 2  (c) 4  (d) 3 
 Sol.26.(b) 2.  The number of images 
 formed when  two mirrors  are placed at 
 an  angle  theta  (  )  to  each  other  is  given ?
 by :  n = (360° /  ) - 1 ?
 So,  here,  we  have  the  mirrors  placed  at 
 an angle  = 120° ?
 n = no. of images formed ?
 n = ( 360° /120° ) - 1 ?
 n = 3 - 1  n = 2 ? ?
 So, a total of two images will be formed. 
 Heat and Thermodynamics 
 Q.27  .  Which  of  the  following  best 
 describes the process of calorimetry? 
 SSC MTS 14/09/2023 (3rd Shift) 
 (a) Measuring the amount of 
 compressive strength 
 (b) Measuring the amount of force 
 (c) Measuring the amount of electricity 
 (d) Measuring the amount of heat energy 
 transferred 
 Sol.27.(d)  Calorimetry  is  the  process  of 
 measuring  the  amount  of  heat  released 
 or  absorbed  during  a  chemical  reaction. 
 By  knowing  the  change  in  heat,  it  can  be 
 determined  whether  or  not  a  reaction  is 
 exothermic  (releases  heat)  or 
 endothermic  (absorbs  heat).  Calorimetry 
 also  plays  a  large  part  of  everyday  life, 
 controlling  the  metabolic  rates  in 
 humans  and  consequently  maintaining 
 such functions like body temperature. 
 Q.28.  In  which  method  of  cooking  is  food 
 heated  slowly  over  a  source  of  heat  and 
 cooked  by  high  heat  and  air  convection 
 depending  on  the  position  of  the  food  in 
 relation to the ?re? 
 SSC CGL 26/07/2023 (2nd shift) 
 (a) Spit-roasting  (b) Braising 
 (c) Poaching  (d) Stewing 
 Sol.28.(a)  Spit-roasting.  Braising  -  The 
 cooking  of  meat  or  vegetables  by  heating 
 them  slowly  with  oil  and  moisture  in  a 
 tightly  sealed  vessel.  Poaching  -  A  moist 
 heat  method  of  cooking  by  submerging 
 food  in  some  kind  of  liquid  and  heating 
 at  a  low  temperature.  Stewing  -  A 
 combination  cooking  method  that  uses 
 small,  uniform  pieces  of  meat  that  are 
 totally  immersed  in  liquid  and  slowly 
 simmered. 
 Q.29.  Who coined the term 'zeroth law of 
 thermodynamics'  in  1931,  which  asserts 
 that  two  bodies  in  equilibrium  with  a  third 
 are in equilibrium with each other? 
 SSC CGL 27/07/2023 (3rd shift) 
 (a) James Clerk Maxwell 
 (b) Max Planck 
 (c) Josiah Willard Gibbs 
 (d) Ralph H. Fowler 
 Sol.29.(d) Ralph H Fowler. 
 Thermodynamics  deals  with  the  relations 
 between  heat  and  other  forms  of  energy. 
 James  Clerk  Maxwell  -  Theory  of 
 electromagnetism.  Max  Planck  -  The 
 quantum  of  action  (Planck's  constant). 
 Josiah  Willard  Gibbs  -  Gibbs  energy 
 (Available energy in a system). 
 Q.30.  Triple point can be de?ned as: 
 Matric Level 28/06/2023 (Shift - 1) 
 (a) the condition of temperature under 
 which the gaseous and liquid phases 
 of a substance can exist in 
 equilibrium 
 (b) the temperature at which solid is 
 converted into liquid 
 (c) the condition of pressure under which 
 the solid and liquid phases of a 
 substance can exist in equilibrium 
 (d) the condition of temperature and 
 pressure under which the gaseous, 
 liquid and solid phases of a 
 substance can exist in equilibrium 
 Sol.30.(d)  The  triple  point  of  water  is  at 
 273.16  kelvin  (0.01  °C  or  32.02  °F)  and  a 
 pressure of 611.7 Pascals. 
 Q.31.  According  to  law,  heat 
 produced  by  an  electric  current  is  directly 
 proportional  to  the  resistance  of  the 
 conductor,  the  square  of  the  current,  and 
 the time for which it ?ows. 
 SSC MTS 17/05/2023 (Afternoon) 
 (a) Hooke's  (b) Charles's 
 (c) Faraday's  (d) Joule's 
 Sol.31.(d)  Joule's.  Joule's  law  of  heating, 
 H  =  I 
 2 
 RT,  where,  H  -  Heat,  I  -  Current,  R  - 
 Resistance,  T  -  time.  Hooke's  law  (law  of 
 elasticity)  -  Discovered  by  the  English 
 scientist  Robert  Hooke  in  1660,  which 
 states  that,  for  relatively  small 
 deformations  of  an  object,  the 
 displacement  or  size  of  the  deformation 
 is  directly  proportional  to  the  deforming 
 force  or  load.  Faraday's  law  -  The 
 magnitude  of  induced  emf  is  equal  to  the 
 rate  of  change  of  ?ux  linkages  with  the 
 coil. 
 Q.32.  Tensile  or  compressive  stress  can 
 also be termed as _______. 
 SSC MTS 13/06/2023 (Morning) 
 (a) longitudinal stress 
 (b) tangential stress 
 (c) hydraulic stress 
 (d) shearing stress 
 Sol.32.(a)  Longitudinal  stress  (axial 
 stress)  .  Other  types  of  stress  :  Tangential 
 stress  is  a  type  of  stress  that  acts 
 perpendicular  to  the  surface  of  an  object. 
 Hydraulic  stress  is  a  type  of  stress  that  is 
 caused  by  the  pressure  of  a  ?uid. 
 Shearing stress is a type of stress that 
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 acts parallel to the surface of an object. 
 Q.33.  In  which  of  the  following  ways  of 
 heat transfer no medium is required? 
 SSC CHSL 09/03/2023 (3rd Shift) 
 (a) Radiation and Conduction both 
 (b) Conduction 
 (c) Convection 
 (d) Radiation 
 Sol.33.(d)  Radiation  :  Energy  that  comes 
 from  a  source  and  travels  through  space 
 at  the  speed  of  light.  It  has  wave-like 
 properties  and  can  be  called 
 “electromagnetic  waves”.  Convection  : 
 Process  of  heat  transfer  by  the 
 movement  of  molecules  within  ?uids 
 such  as  gasses  and  liquids.  Conduction  : 
 Process  by  which  heat  energy  is 
 transmitted  through  collisions  between 
 neighbouring atoms or molecules. 
 Q.34.  ______  is  de?ned  as  the 
 temperature  to  which  the  air  would  have 
 to  cool  (at  constant  pressure  and 
 constant  water  vapour  content)  in  order 
 to reach saturation. 
 SSC CGL 13/04/2022 (Afternoon) 
 (a) Dew point temperature 
 (b) Air temperature 
 (c) Relative humidity 
 (d) Surface temperature 
 Sol.34.(a)  Dew  point  temperature.  It  is 
 the  temperature  the  air  needs  to  be 
 cooled  to  (at  constant  pressure)  in  order 
 to achieve a relative humidity of 100%. 
 Q.35.  What  is  the  Steam  Point  on  the 
 Fahrenheit scale? 
 SSC MTS 13/10/2021 (Morning) 
 (a) 32 
 ° 
 F  (b) 100 
 ° 
 F   (c) 212 
 ° 
 F   (d) 80 
 ° 
 F 
 Sol.35.(c)  212 
 ° 
 F .  Steam  point  is  the 
 temperature  at  which  the  maximum 
 vapour  pressure  of  water  is  equal  to  one 
 atmosphere.  It  has  a  value  of  100°C  on 
 the Celsius scale. 
 Q.36.  Heat,  in  ______,  is  a  type  of  energy 
 transfer  from  a  warmer  substance  to  a 
 colder one. 
 SSC CHSL 06/08/2021 (Morning) 
 (a) gravity  (b) friction 
 (c) thermodynamics        (d) magnet 
 Sol.36.(c)  Thermodynamics  .  During 
 energy  transfer,  the  energy  moves  from 
 the  hotter  object  to  the  colder  object. 
 This  means  that  the  hotter  object  will 
 cool  down  and  the  colder  object  will 
 warm  up.  The  energy  transfer  will 
 continue  until  both  objects  are  at  the 
 same temperature. Heat is measured in 
 joules (J). 
 Q.37.  _______  expansion  makes  the  Eiffel 
 Tower taller during summers. 
 SSC CGL 04/03/2020 (Morning) 
 (a) thermal  (b) slope 
 (c) gravitational  (d) chemical 
 Sol.37.(a)  Thermal  expansion  is  a 
 phenomenon  due  to  which  the  metal 
 expands  when  heated  and  contracts 
 when  cooled.  The  Eiffel  Tower  gets  taller 
 by up to  6 inches during the summer. 
 Fluid Mechanics 
 Q.38.  In  1851,  who  founded  the  science 
 of  hydrodynamics  with  his  law  of 
 viscosity  describing  the  velocity  of  a 
 small sphere through a viscous ?uid? 
 SSC CHSL 09/08/2023 (4th shift) 
 (a) Daniel Bernoulli 
 (b) George Gabriel Stokes 
 (c) Evangelista Torricelli 
 (d) Heinrich Gustav Magnus 
 Sol.38.(b)  George  Gabriel  Stokes.  Daniel 
 Bernoulli  -  Known  for  Bernoulli's 
 principle.  According  to  this  principle,  an 
 increase  in  the  speed  of  a  ?uid  occurs 
 simultaneously  with  a  decrease  in 
 pressure  or  a  decrease  in  the  ?uid's 
 potential  energy.  Evangelista  Torricelli  - 
 Known  for  his  invention  of  the  barometer, 
 a  device  used  to  measure  atmospheric 
 pressure.  Heinrich  Gustav  Magnus  - 
 Known  for  Magnus  effect,  an  observable 
 phenomenon  that  is  commonly 
 associated  with  a  spinning  object 
 moving through the air or a ?uid. 
 Q.39.  Whose  law  states  that  total  energy 
 per  unit  mass  of  ?owing  ?uid,  at  any 
 point  in  the  subsurface,  is  the  sum  of  the 
 kinetic,  potential,  and  ?uid-pressure 
 energy and is equal to a constant value? 
 SSC CGL 19/07/2023 (3rd shift) 
 (a) Daniel Bernoulli 
 (b) Evangelista Torricelli 
 (c) Blaise Pascal 
 (d) Marie Poiseuille 
 Sol.39.(a)  Daniel  Bernoulli.  Torricelli's 
 law  -  The  parting  speed  of  a  jet  of  water, 
 based  on  the  distance  below  the  surface 
 at  which  the  jet  starts,  assuming  no  air 
 resistance,  viscosity,  or  other  hindrance 
 to  the  ?uid  ?ow.  Pascal's  law  -  The 
 pressure  applied  to  an  enclosed  ?uid  will 
 be  transmitted  without  a  change  in 
 magnitude  to  every  point  of  the  ?uid  and 
 the  walls  of  the  container.  Poiseuille's 
 law  -  It  gives  the  pressure  drop  in  an 
 incompressible  and  Newtonian  ?uid  in 
 laminar  ?ow  ?owing  through  a  long 
 cylindrical pipe of a constant 
 cross-section. 
 Q.40.  _______  forces  water  through  a 
 semipermeable  membrane  and  removes 
 contaminants. 
 SSC CHSL 16/03/2023 (4th Shift) 
 (a) Boiling  (b) Distillation 
 (c) Reverse Osmosis        (d) Filtration 
 Sol.40.(c)  Reverse  Osmosis  .  Filtration  is 
 the  process  in  which  solid  particles  in  a 
 liquid  or  gaseous  ?uid  are  removed. 
 Boiling  is  the  process  by  which  a  liquid 
 turns  into  a  vapor  when  it  is  heated  to  its 
 boiling  point.  Distillation  is  a  process 
 involving  the  conversion  of  a  liquid  into 
 vapor  that  is  subsequently  condensed 
 back to liquid form. 
 Q.41.  What is the relative density of silver 
 SSC CHSL 19/03/2020 (Evening) 
 (a) 9.5  (b) 7.2  (c) 10.4  (d) 10.8 
 Sol.41.(d)  10.8.  Relative  density  is  a 
 comparative  measure  of  the  density  of  a 
 substance  to  the  density  of  a  reference 
 substance (Usually Water). 
 Electric Current and Its Effects 
 Q.42.  The  neutral  point  in  the  magnetic 
 ?eld  of  a  horizontally  positioned  bar 
 magnet is the : 
 SSC CHSL 02/08/2023 (2nd shift) 
 (a) point where the magnetic ?eld 
 changes direction 
 (b) point where the magnetic ?eld is the 
 weakest 
 (c) point where the magnetic ?eld is the 
 strongest 
 (d) point where the magnetic ?eld is zero 
 Sol.42.(d)  Neutral  point  :  The  point  at 
 which  the  resultant  magnetic  ?eld  is 
 zero.  It  is  a  point  where  the  magnetic 
 ?eld  produced  due  to  a  bar  magnet  is 
 completely  balanced  by  the  horizontal 
 component  of  Earth's  magnetic  ?eld. 
 Magnetic  Field  -  The  region  around  a 
 magnetic  material  or  a  moving  electric 
 charge  within  which  the  force  of 
 magnetism  acts.  Types  of  magnets  : 
 Permanent  magnet,  temporary  magnet 
 and electromagnet. 
 Q.43.  In  1834,  who  proposed  a  law  that 
 states  that  the  current  induced  by  a 
 change  in  ?ow  opposes  the  effect 
 producing the change ? 
 SSC CHSL 02/08/2023 (4th shift) 
 (a) David Brewster 
 (b) Henry Moseley 
 (c) Christian Johann Doppler 
 (d) Heinrich Friedrich Lenz 
 Sol.43.(d)  Heinrich  Friedrich  Lenz. 
 Lenz’s  law  -  An  induced  electric  current 
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 ?ows  in  a  direction  such  that  the  current 
 opposes  the  change  that  induced  it. 
 Lenz’s  law  is  used  in  electromagnetic 
 brakes  and  induction  cooktops.  It  is  also 
 applied  to  electric  generators,  AC 
 generators.  Christian  Johann  Doppler  - 
 Doppler’s  effect  refers  to  the  change  in 
 wave  frequency  during  the  relative 
 motion  between  a  wave  source  and  its 
 observer.  Sir  David  Brewster  -  Brewster 
 law  is  a  statement  that  says  that  when 
 unpolarized  light  falls  on  an  interface,  the 
 re?ected  light  is  completely  polarized  if 
 the  angle  of  incidence  is  a  speci?c  angle 
 called the Brewster's angle. 
 Q.44.  Which  of  the  following  options  is 
 correct for Coulomb's law? 
 SSC CHSL 07/08/2023 (2nd shift) 
 (a) Valid for both point and distributed 
 charges 
 (b) Valid for only distributed charge 
 (c) Valid for only point charge 
 (d) Valid for neither point charge nor 
 distributed charge 
 Sol.44.(c)  Valid  for  only  point  charge. 
 Coulomb’s  Law  :  The  electrical  force 
 between  two  charged  objects  is  directly 
 proportional  to  the  product  of  the 
 quantity  of  charge  on  the  objects  and 
 inversely  proportional  to  the  square  of 
 the  separation  distance  between  the  two 
 objects.  F  =  ,  where  {Q 
 1 
 -  quantity 
 ??     ?? 
 1 
    ?? 
 2 
 ?? 
 2 
 of  charge  on  object  1  (in  Coulombs),  Q 
 2 
 - 
 quantity  of  charge  on  object  2  (in 
 Coulombs),  and  d  -  distance  of 
 separation  between  the  two  objects  (in 
 meters).  k  -  proportionality  constant  (the 
 Coulomb's  law  constant)}.  Value  of  k  - 
 8.988×10 
 9 
 Nm 
 2 
 /C 
 2 
 . 
 Q.45.  Which  of  the  following  laws  state 
 that  “The  magnitude  of  the  induced  EMF 
 in  a  circuit  is  equal  to  the  time  rate  of 
 change  of  magnetic  ?ux  through  the 
 circuit”? 
 SSC CHSL 09/08/2023 (2nd shift) 
 (a) Faraday’s law  (b) Coulomb’s law 
 (c) Kirchhoff’s laws   (d) Laplace’s law 
 Sol.45.(a)  Faraday's  law.  Coulomb's  law 
 states  that  the  force  between  two 
 charged  particles  is  directly  proportional 
 to  the  product  of  their  charges  and 
 inversely  proportional  to  the  square  of 
 the  distance  between  them.  Kirchhoff's 
 laws  -  The  algebraic  sum  of  all  the 
 currents  meeting  at  a  point  in  a  circuit  is 
 equal  to  zero.  Laplace's  law  -  The  tension 
 in  the  walls  of  a  hollow  sphere  or  cylinder 
 is dependent on the pressure of its 
 contents and its radius. 
 Q.46.  Which  of  the  following  is  the 
 proper  number  of  electrons  in  1  A  of 
 current? 
 SSC CHSL 17/08/2023 (1st shift) 
 (a) 6.25  10 
 21 
 (b) 6.25  10 
 18 
× ×
 (c) 6.25  10 
 19 
 (d) 6.25  10 
 15 
× ×
 Sol.46.(b)  6.25  ×  10 
 18 
 .  Electric  Current  - 
 The  rate  of  ?ow  of  electrons  in  a 
 conductor.  SI  Unit  -  Ampere  (A). 
 Conductors  are  de?ned  as  the  materials 
 or  substances  that  allow  electricity  to 
 ?ow  through  them.  Examples  -  Human 
 body,  aqueous  solutions  of  salts  and 
 metals  like  iron,  silver  and  gold. 
 Insulators  are  materials  that  restrict  the 
 free  ?ow  of  electrons  from  one  particle 
 to  another.  Examples  -  Plastic,  Wood, 
 Rubber and Glass. 
 Q.47.  Which of the following has the 
 highest value of resistivity? 
 SSC CGL 17/07/2023 (1st shift) 
 (a) Silver  (b) Nichrome 
 (c) Chromium  (d) Iron 
 Sol.47.(b)  Nichrome.  Resistivity  -  It  is  the 
 measure  of  the  resistance  ability  of  a 
 material  to  oppose  the  ?ow  of  current. 
 Electrical  resistivity  is  the  reciprocal  of 
 electrical  conductivity.  High  Resistivity 
 materials  -  Ebonite,  Tungsten,  Carbon. 
 High  conductivity  materials  -  Copper, 
 iron, gold, aluminium, and silver. 
 Q.48.  Which  of  the  following  elements  is 
 highly  effective  for  making  a  permanent 
 magnet? 
 SSC CGL 26/07/2023 (2nd shift) 
 (a) Zinc  (b)Aluminum(c) Copper (d) Steel 
 Sol.48.(d)  Steel.  Permanent  magnets  are 
 made  from  special  alloys  (ferromagnetic 
 materials)  such  as  iron,  nickel  and  cobalt, 
 several  alloys  of  rare-earth  metals  and 
 minerals  such  as  lodestone;  Used  in 
 headphones,  loudspeakers,  MRI 
 Scanners,  hard  disc  drives,  generators, 
 transducers.  A  freely  suspended  magnet 
 always  rests  in  north-south  (N-S) 
 direction.  Magnetite  (Fe 
 3 
 O 
 4 
 )  -  An  ore  of 
 iron  that  has  magnetic  properties 
 (ferrimagnetic). 
 Q.49.  If  four  resistors  of  3  O,  4  O,  5O  and 
 6O  are  connected  in  series,  what  will  be 
 the  combined  resistance  of  the  four 
 resistors? 
 Matric Level 27/06/2023 (Shift - 2) 
 (a) 3O  (b) 9O  (c) 18O  (d) 10O 
 Sol.49.(c)  18O.  In  series  connection  of 
 resistors  (Here,  3  O,  4  O,  5  O,  6  O),  Current 
 through  each  resistor  is  same.  Voltage 
 drop  across  each  resistor  is  proportional 
 to  its  resistance.  The  total  resistance  is 
 equal  to  the  sum  of  the  individual 
 resistances.  Equivalent  resistance  R 
 n 
 =  R 
 1 
 +  R 
 2 
 +  R 
 3 
 +  R 
 4 
 =  3  O  +  4  O  +  5  O  +  6  O  = 
 18O. 
 Q.50.  When  will  you  ?nd  the  magnetic 
 ?eld stronger? 
 Graduate Level 30/06/2023 ( Shift - 1) 
 (a) When ?eld lines are crowded 
 (b) When the lines are together 
 (c) When the ?eld lines are not seen 
 (d) When the poles are together 
 Sol.50.(a)  Magnetic  ?elds  (Symbol  B  or 
 H,  Unit  -  Tesla)  :  William  Gilbert 
 discovered  that  the  Earth  is  a  magnet  . 
 The  strength  of  magnetic  ?eld  lines 
 depends  on  how  close  the  magnetic  ?eld 
 lines  are.  Some  properties  related  to 
 magnetic  ?eld  lines  are:  Strongest  near 
 the  poles  (N  or  S),  never  crosses  each 
 other, always make closed loops. 
 Q.51.  Which  of  the  following  materials  is 
 a conductor of electricity ? 
 SSC MTS 08/05/2023 (Afternoon) 
 (a) Silver  (b) Glass  (c) Mica  (d) Ebonite 
 Sol.51.(a)  Silver.  The  material  that 
 allows  ?ow  of  electric  current  with  little 
 or  no  resistance  are  called  conductors. 
 Examples  -  Copper,  Aluminum,  human 
 body.  Glass,  mica,  rubber  and  Ebonite  are 
 insulators  . 
 Q.52.  Which  device  is  used  to  either 
 break an electric circuit or to complete it? 
 SSC MTS 08/05/2023 (Morning) 
 (a) Insulators (b) Wires (c) Switch (d) Bulb 
 Sol.52.(c)  Switch  -  It  is  a  device  used  to 
 interrupt  the  ?ow  of  electrons  in  a  circuit. 
 Insulator  -  A  material  in  which  electric 
 current  does  not  ?ow  freely.  Examples  - 
 Glass, air, wood, plastic and rubber. 
 Q.53.  Identify the correct statement. 
 SSC CGL Tier II  02/03/2023 
 (a) Resistance of a wire depends on the 
 length and density of the wire. 
 (b) Speci?c resistance is the same for all 
 conductors. 
 (c) Resistance of a wire depends on the 
 length and cross-section of the wire. 
 (d) Speci?c resistance is dependent on 
 the cross-sectional area of the wire. 
 Sol.53.(c)  The  resistance  of  a  wire  is 
 directly  proportional  to  its  length  and 
 inversely  proportional  to  its  cross 
 -sectional  area.  Resistance  is  a  measure 
 of  the  opposition  to  current  ?ow  in  an 
 electrical  circuit.  It  is  measured  in  ohm 
 (O).  Factors  affecting  resistance  - 
 Material's  conductivity,  Length, 
 Cross-sectional area and Temperature. 
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