CBSE Physics Past year paper - 2019, Class 12 Class 12 Notes | EduRev

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Class 12 : CBSE Physics Past year paper - 2019, Class 12 Class 12 Notes | EduRev

 Page 1


  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
CBSE 
Class XII Physics 
Board Paper - 2019 
Time: 3 hours                                                                Maximum Marks: 70 
  
General Instructions:                                                                                                                     
(i) All questions are compulsory. There are 27 questions in all. 
(ii) This question paper has four sections: Section A, Section B, Section C, and 
Section D. 
(iii) Section A contains five questions of one mark each, section B contains seven 
questions of two marks each, section C contains twelve questions of three 
marks each, section D contains three questions of five marks each.  
(iv) There is no overall choice. However, an internal choice has been provided in 
two question of one mark, two question of two marks, four questions of 
three marks and three questions of five marks weightage. You have to 
attempt only one of the choices in such questions.  
(v) You may use the following values of physical constants wherever necessary: 
c = 3 ? 10
8
 m/s 
h = 6.63 ? 10
-34
 Js 
e = 1.6 ? 10
-19
 C 
µ
0
 = 4 p ? 10
-7 
T mA
-l
 
?
0
 = 8.854 ? 10
-12
 C
2
 N
-1
 m
-2
 
0
1
4 ??
 = 9 ? 10
9
 N m
2  
C
-2
 
Mass of electron
 
= 9.1 ? 10
-31
 kg 
Mass of neutron = 1.675 ? 10
-27
 kg 
Mass of proton = 1.673 ? 10
-27
 kg 
Avogadro’s number = 6.023 ? 10
23
 per gram mole 
Boltzmann constant = 1.38 ? 10
-23
 J K
-1
 
 
  
Page 2


  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
CBSE 
Class XII Physics 
Board Paper - 2019 
Time: 3 hours                                                                Maximum Marks: 70 
  
General Instructions:                                                                                                                     
(i) All questions are compulsory. There are 27 questions in all. 
(ii) This question paper has four sections: Section A, Section B, Section C, and 
Section D. 
(iii) Section A contains five questions of one mark each, section B contains seven 
questions of two marks each, section C contains twelve questions of three 
marks each, section D contains three questions of five marks each.  
(iv) There is no overall choice. However, an internal choice has been provided in 
two question of one mark, two question of two marks, four questions of 
three marks and three questions of five marks weightage. You have to 
attempt only one of the choices in such questions.  
(v) You may use the following values of physical constants wherever necessary: 
c = 3 ? 10
8
 m/s 
h = 6.63 ? 10
-34
 Js 
e = 1.6 ? 10
-19
 C 
µ
0
 = 4 p ? 10
-7 
T mA
-l
 
?
0
 = 8.854 ? 10
-12
 C
2
 N
-1
 m
-2
 
0
1
4 ??
 = 9 ? 10
9
 N m
2  
C
-2
 
Mass of electron
 
= 9.1 ? 10
-31
 kg 
Mass of neutron = 1.675 ? 10
-27
 kg 
Mass of proton = 1.673 ? 10
-27
 kg 
Avogadro’s number = 6.023 ? 10
23
 per gram mole 
Boltzmann constant = 1.38 ? 10
-23
 J K
-1
 
 
  
  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
SECTION – A 
Q. 1 Draw a plot of resistivity versus temperature for a typical semiconductor. [1] 
 
Q. 2 Define the term ‘attenuation’ in communication system.  [1] 
 
Q. 3 Two metallic spheres A and B kept on insulating stands are in contact with 
each other. A positively charged rod P is brought near the sphere A as shown in the 
figure. The two spheres are separated from each other, and the rod P is removed. 
What will be the nature of charges on spheres A and B? [1] 
 
 
OR 
A metal sphere is kept on an insulating stand. A negatively charged rod is brought 
near it, then the sphere is earthed as shown. On removing the earthing, and taking 
the negatively charged rod away, what will be the nature of charge on the sphere? 
Give reason for your answer. 
 
 
Q. 4 In photoelectric emission, when the frequency of incident radiation in 
Photoelectric effect is doubled, will the maximum kinetic energy of photoelectrons 
also be doubled? Justify your answer. [1] 
 
Page 3


  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
CBSE 
Class XII Physics 
Board Paper - 2019 
Time: 3 hours                                                                Maximum Marks: 70 
  
General Instructions:                                                                                                                     
(i) All questions are compulsory. There are 27 questions in all. 
(ii) This question paper has four sections: Section A, Section B, Section C, and 
Section D. 
(iii) Section A contains five questions of one mark each, section B contains seven 
questions of two marks each, section C contains twelve questions of three 
marks each, section D contains three questions of five marks each.  
(iv) There is no overall choice. However, an internal choice has been provided in 
two question of one mark, two question of two marks, four questions of 
three marks and three questions of five marks weightage. You have to 
attempt only one of the choices in such questions.  
(v) You may use the following values of physical constants wherever necessary: 
c = 3 ? 10
8
 m/s 
h = 6.63 ? 10
-34
 Js 
e = 1.6 ? 10
-19
 C 
µ
0
 = 4 p ? 10
-7 
T mA
-l
 
?
0
 = 8.854 ? 10
-12
 C
2
 N
-1
 m
-2
 
0
1
4 ??
 = 9 ? 10
9
 N m
2  
C
-2
 
Mass of electron
 
= 9.1 ? 10
-31
 kg 
Mass of neutron = 1.675 ? 10
-27
 kg 
Mass of proton = 1.673 ? 10
-27
 kg 
Avogadro’s number = 6.023 ? 10
23
 per gram mole 
Boltzmann constant = 1.38 ? 10
-23
 J K
-1
 
 
  
  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
SECTION – A 
Q. 1 Draw a plot of resistivity versus temperature for a typical semiconductor. [1] 
 
Q. 2 Define the term ‘attenuation’ in communication system.  [1] 
 
Q. 3 Two metallic spheres A and B kept on insulating stands are in contact with 
each other. A positively charged rod P is brought near the sphere A as shown in the 
figure. The two spheres are separated from each other, and the rod P is removed. 
What will be the nature of charges on spheres A and B? [1] 
 
 
OR 
A metal sphere is kept on an insulating stand. A negatively charged rod is brought 
near it, then the sphere is earthed as shown. On removing the earthing, and taking 
the negatively charged rod away, what will be the nature of charge on the sphere? 
Give reason for your answer. 
 
 
Q. 4 In photoelectric emission, when the frequency of incident radiation in 
Photoelectric effect is doubled, will the maximum kinetic energy of photoelectrons 
also be doubled? Justify your answer. [1] 
 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
Q. 5 State the condition under which a large magnification can be achieved in an 
instrumental telescope 
OR 
How does the angle of minimum deviation of a glass prism vary if the incident violet 
light is replaced by a red light? [1] 
 
SECTION – B 
Q. 6 show that image formed by convex mirror of an object is always virtual.     [2] 
 
Q. 7 Distinguish between nuclear fusion and nuclear fission. Give one example for 
each.  [2] 
 
Q. 8 An electron in a hydrogen atom in the second excited state jumps to the first 
and ground state of the atom. Find the ratio of the wavelengths excited during this 
process.  [2] 
 
Q. 9 Five point charges, each of charge + q are placed on five vertices of a regular 
hexagon of side ‘l’. Find the magnitude of the resultant force on a charge – q placed 
at the centre of the hexagon.  [2] 
OR 
A simple pendulum consists of small sphere of mass m suspended by a thread of 
length l. The sphere carries a positive charge q. The pendulum is placed in a 
uniform electric field of strength E directed vertically downwards. Find the period of 
oscillation of the pendulum due to the electrostatic force acting on the sphere, 
neglecting the effect of the gravitational force. [2] 
 
Q. 10 Plot a graph showing the variation of undecayed nuclei N versus time t. From 
the graph, find out how one can determine the half-life and average life of the 
radioactive nuclei. [2] 
 
Q. 11 A 0.5 m long solenoid of 10 turns/cm has area of cross-section 1 cm
2
. 
Calculate the voltage induced across its ends if the current in the solenoid is 
changed from 1 A to 2 A in 0.1 s.           [2] 
OR 
Page 4


  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
CBSE 
Class XII Physics 
Board Paper - 2019 
Time: 3 hours                                                                Maximum Marks: 70 
  
General Instructions:                                                                                                                     
(i) All questions are compulsory. There are 27 questions in all. 
(ii) This question paper has four sections: Section A, Section B, Section C, and 
Section D. 
(iii) Section A contains five questions of one mark each, section B contains seven 
questions of two marks each, section C contains twelve questions of three 
marks each, section D contains three questions of five marks each.  
(iv) There is no overall choice. However, an internal choice has been provided in 
two question of one mark, two question of two marks, four questions of 
three marks and three questions of five marks weightage. You have to 
attempt only one of the choices in such questions.  
(v) You may use the following values of physical constants wherever necessary: 
c = 3 ? 10
8
 m/s 
h = 6.63 ? 10
-34
 Js 
e = 1.6 ? 10
-19
 C 
µ
0
 = 4 p ? 10
-7 
T mA
-l
 
?
0
 = 8.854 ? 10
-12
 C
2
 N
-1
 m
-2
 
0
1
4 ??
 = 9 ? 10
9
 N m
2  
C
-2
 
Mass of electron
 
= 9.1 ? 10
-31
 kg 
Mass of neutron = 1.675 ? 10
-27
 kg 
Mass of proton = 1.673 ? 10
-27
 kg 
Avogadro’s number = 6.023 ? 10
23
 per gram mole 
Boltzmann constant = 1.38 ? 10
-23
 J K
-1
 
 
  
  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
SECTION – A 
Q. 1 Draw a plot of resistivity versus temperature for a typical semiconductor. [1] 
 
Q. 2 Define the term ‘attenuation’ in communication system.  [1] 
 
Q. 3 Two metallic spheres A and B kept on insulating stands are in contact with 
each other. A positively charged rod P is brought near the sphere A as shown in the 
figure. The two spheres are separated from each other, and the rod P is removed. 
What will be the nature of charges on spheres A and B? [1] 
 
 
OR 
A metal sphere is kept on an insulating stand. A negatively charged rod is brought 
near it, then the sphere is earthed as shown. On removing the earthing, and taking 
the negatively charged rod away, what will be the nature of charge on the sphere? 
Give reason for your answer. 
 
 
Q. 4 In photoelectric emission, when the frequency of incident radiation in 
Photoelectric effect is doubled, will the maximum kinetic energy of photoelectrons 
also be doubled? Justify your answer. [1] 
 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
Q. 5 State the condition under which a large magnification can be achieved in an 
instrumental telescope 
OR 
How does the angle of minimum deviation of a glass prism vary if the incident violet 
light is replaced by a red light? [1] 
 
SECTION – B 
Q. 6 show that image formed by convex mirror of an object is always virtual.     [2] 
 
Q. 7 Distinguish between nuclear fusion and nuclear fission. Give one example for 
each.  [2] 
 
Q. 8 An electron in a hydrogen atom in the second excited state jumps to the first 
and ground state of the atom. Find the ratio of the wavelengths excited during this 
process.  [2] 
 
Q. 9 Five point charges, each of charge + q are placed on five vertices of a regular 
hexagon of side ‘l’. Find the magnitude of the resultant force on a charge – q placed 
at the centre of the hexagon.  [2] 
OR 
A simple pendulum consists of small sphere of mass m suspended by a thread of 
length l. The sphere carries a positive charge q. The pendulum is placed in a 
uniform electric field of strength E directed vertically downwards. Find the period of 
oscillation of the pendulum due to the electrostatic force acting on the sphere, 
neglecting the effect of the gravitational force. [2] 
 
Q. 10 Plot a graph showing the variation of undecayed nuclei N versus time t. From 
the graph, find out how one can determine the half-life and average life of the 
radioactive nuclei. [2] 
 
Q. 11 A 0.5 m long solenoid of 10 turns/cm has area of cross-section 1 cm
2
. 
Calculate the voltage induced across its ends if the current in the solenoid is 
changed from 1 A to 2 A in 0.1 s.           [2] 
OR 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
A small flat search coil of area 5 cm
2
 with 140 closely wound turns is placed 
between the poles of a powerful magnet producing magnetic field 0.09 T and then 
quickly removed out of the field region. Calculate 
(a) change of magnetic flux through the coil, and 
(b) emf induced in the coil. 
 
Q. 12  [2] 
The figure shows a network of five capacitors connected to a 100 V supply. 
Calculate the total energy stored in the network. 
 
 
SECTION – C 
Q. 13 In the circuit given below, find the voltmeter reading across a 4 O resistor. [3] 
 
 
Q. 14 When a parallel plate capacitor is being charged by a dc battery, why does a 
galvanometer show a momentary deflection? 
Obtain the expression for the displacement current and show how it is related to 
conduction current in a steady state.  [3] 
 
 
Page 5


  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
CBSE 
Class XII Physics 
Board Paper - 2019 
Time: 3 hours                                                                Maximum Marks: 70 
  
General Instructions:                                                                                                                     
(i) All questions are compulsory. There are 27 questions in all. 
(ii) This question paper has four sections: Section A, Section B, Section C, and 
Section D. 
(iii) Section A contains five questions of one mark each, section B contains seven 
questions of two marks each, section C contains twelve questions of three 
marks each, section D contains three questions of five marks each.  
(iv) There is no overall choice. However, an internal choice has been provided in 
two question of one mark, two question of two marks, four questions of 
three marks and three questions of five marks weightage. You have to 
attempt only one of the choices in such questions.  
(v) You may use the following values of physical constants wherever necessary: 
c = 3 ? 10
8
 m/s 
h = 6.63 ? 10
-34
 Js 
e = 1.6 ? 10
-19
 C 
µ
0
 = 4 p ? 10
-7 
T mA
-l
 
?
0
 = 8.854 ? 10
-12
 C
2
 N
-1
 m
-2
 
0
1
4 ??
 = 9 ? 10
9
 N m
2  
C
-2
 
Mass of electron
 
= 9.1 ? 10
-31
 kg 
Mass of neutron = 1.675 ? 10
-27
 kg 
Mass of proton = 1.673 ? 10
-27
 kg 
Avogadro’s number = 6.023 ? 10
23
 per gram mole 
Boltzmann constant = 1.38 ? 10
-23
 J K
-1
 
 
  
  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
SECTION – A 
Q. 1 Draw a plot of resistivity versus temperature for a typical semiconductor. [1] 
 
Q. 2 Define the term ‘attenuation’ in communication system.  [1] 
 
Q. 3 Two metallic spheres A and B kept on insulating stands are in contact with 
each other. A positively charged rod P is brought near the sphere A as shown in the 
figure. The two spheres are separated from each other, and the rod P is removed. 
What will be the nature of charges on spheres A and B? [1] 
 
 
OR 
A metal sphere is kept on an insulating stand. A negatively charged rod is brought 
near it, then the sphere is earthed as shown. On removing the earthing, and taking 
the negatively charged rod away, what will be the nature of charge on the sphere? 
Give reason for your answer. 
 
 
Q. 4 In photoelectric emission, when the frequency of incident radiation in 
Photoelectric effect is doubled, will the maximum kinetic energy of photoelectrons 
also be doubled? Justify your answer. [1] 
 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
Q. 5 State the condition under which a large magnification can be achieved in an 
instrumental telescope 
OR 
How does the angle of minimum deviation of a glass prism vary if the incident violet 
light is replaced by a red light? [1] 
 
SECTION – B 
Q. 6 show that image formed by convex mirror of an object is always virtual.     [2] 
 
Q. 7 Distinguish between nuclear fusion and nuclear fission. Give one example for 
each.  [2] 
 
Q. 8 An electron in a hydrogen atom in the second excited state jumps to the first 
and ground state of the atom. Find the ratio of the wavelengths excited during this 
process.  [2] 
 
Q. 9 Five point charges, each of charge + q are placed on five vertices of a regular 
hexagon of side ‘l’. Find the magnitude of the resultant force on a charge – q placed 
at the centre of the hexagon.  [2] 
OR 
A simple pendulum consists of small sphere of mass m suspended by a thread of 
length l. The sphere carries a positive charge q. The pendulum is placed in a 
uniform electric field of strength E directed vertically downwards. Find the period of 
oscillation of the pendulum due to the electrostatic force acting on the sphere, 
neglecting the effect of the gravitational force. [2] 
 
Q. 10 Plot a graph showing the variation of undecayed nuclei N versus time t. From 
the graph, find out how one can determine the half-life and average life of the 
radioactive nuclei. [2] 
 
Q. 11 A 0.5 m long solenoid of 10 turns/cm has area of cross-section 1 cm
2
. 
Calculate the voltage induced across its ends if the current in the solenoid is 
changed from 1 A to 2 A in 0.1 s.           [2] 
OR 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
A small flat search coil of area 5 cm
2
 with 140 closely wound turns is placed 
between the poles of a powerful magnet producing magnetic field 0.09 T and then 
quickly removed out of the field region. Calculate 
(a) change of magnetic flux through the coil, and 
(b) emf induced in the coil. 
 
Q. 12  [2] 
The figure shows a network of five capacitors connected to a 100 V supply. 
Calculate the total energy stored in the network. 
 
 
SECTION – C 
Q. 13 In the circuit given below, find the voltmeter reading across a 4 O resistor. [3] 
 
 
Q. 14 When a parallel plate capacitor is being charged by a dc battery, why does a 
galvanometer show a momentary deflection? 
Obtain the expression for the displacement current and show how it is related to 
conduction current in a steady state.  [3] 
 
 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2019 
 
     
Q. 15                [3] 
a) An ac circuit as shown in the figure has an inductor of inductance L and a 
resistor of resistance R connected in series. Using the phasor diagram, explain 
why the voltage in the circuit will lead the current in phase. 
b) The potential difference across the resistor is 160 V and that across the inductor 
is 120 V. Find the effective value of the applied voltage. If the effective current 
in the circuit be 1.0 A, calculate the total impedance of the circuit. 
c) What will be the potential difference in the circuit when direct current is passed 
through the circuit? 
 
 
OR 
An ac circuit consists of a series combination of circuit elements X and Y. The 
current is ahead of the voltage in phase by
4
?
. If element X is a pure resistor of 100 
O. 
(a) Name the circuit element Y. 
(b) Calculate the rms value of current, if rms value of voltage is 141 V. 
(c) What will happen if the ac source is replaced by a dc source? 
 
Q. 16  [3] 
(a) Explain briefly, using a proper diagram the difference in behaviour of a 
conductor and a dielectric in the presence of external electric field. 
(b) Define the term polarization of a dielectric and write the expression for a linear 
isotropic dielectric in terms of electric field.    
 
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