CBSE Physics Past year paper - 2016, Class 12 | Additional Study Material for NEET PDF Download

 Page 1


  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
CBSE 
Class XII Physics 
Board Paper – 2016 
Time: 3 hours                                                                Maximum Marks: 70 
  
General Instructions:                                                                                                                     
(i) All questions are compulsory. There are 26 questions in all. 
(ii) This question paper has five sections: Section A, Section B, Section, Section D 
and Section E. 
(iii) Section A contains five questions of one mark each, section B contains five 
questions of two marks each, section C contains twelve questions of three 
marks each, section D contains one value based question of four marks and 
section E contains three questions of five marks each.  
(iv) There is no overall choice. However, an internal choice has been provided in 
one question of two marks, one question of three marks and all the 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
 
m
e 
= 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
 
 
SECTION – A 
 
Q. 1 A signal of 5 kHz frequency is amplitude modulated on a carrier wave of 
frequency 2 MHz. What are the frequencies of the side bands produced?  [1] 
 
Q. 2 What can be the causes of helical motion of a charged particle??  [1] 
 
Q. 3 Define mobility of a charge carrier. What is its relation with relaxation time?        
                [1] 
 
Q. 4 What is the amount of work done in moving a point charge Q around a circular 
arc of radius ‘r’ at the centre of which another point charge ‘q’ is located? [1] 
Page 2


  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
CBSE 
Class XII Physics 
Board Paper – 2016 
Time: 3 hours                                                                Maximum Marks: 70 
  
General Instructions:                                                                                                                     
(i) All questions are compulsory. There are 26 questions in all. 
(ii) This question paper has five sections: Section A, Section B, Section, Section D 
and Section E. 
(iii) Section A contains five questions of one mark each, section B contains five 
questions of two marks each, section C contains twelve questions of three 
marks each, section D contains one value based question of four marks and 
section E contains three questions of five marks each.  
(iv) There is no overall choice. However, an internal choice has been provided in 
one question of two marks, one question of three marks and all the 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
 
m
e 
= 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
 
 
SECTION – A 
 
Q. 1 A signal of 5 kHz frequency is amplitude modulated on a carrier wave of 
frequency 2 MHz. What are the frequencies of the side bands produced?  [1] 
 
Q. 2 What can be the causes of helical motion of a charged particle??  [1] 
 
Q. 3 Define mobility of a charge carrier. What is its relation with relaxation time?        
                [1] 
 
Q. 4 What is the amount of work done in moving a point charge Q around a circular 
arc of radius ‘r’ at the centre of which another point charge ‘q’ is located? [1] 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
Q. 5 Why can’t we see clearly through fog? Name the phenomenon responsible for 
it. [1] 
 
SECTION – B 
Q. 6 When is H
?
 line in the emission spectrum of hydrogen atom obtained? 
Calculate the frequency of the photon emitted during this transition.  
          
OR 
Calculate the wavelength of radiation emitted when electron in a hydrogen 
atom jumps from n = ? to n = 1.          [2] 
 
Q. 7 When 5 V potential difference is applied across a wire of length 0.1 m, the drift 
speed of electrons is 2.5 ? 10
-4
 m/s. If the electron density in the wire is 8 ? 
10
28
 m
-3
, calculate the resistivity of the material of the wire. [2] 
 
Q. 8 A proton and an ?-particle are accelerated through the same potential 
difference. Which one of the two has (i) greater de-Broglie wavelength, and 
(ii) less kinetic energy? Justify your answer.         [2] 
 
Q. 9 A ray PQ incident on the refracting face BA is refracted in the prism BAC as 
shown in the figure and emerges from the other refracting face AC as RS such 
that AQ = AR. If the angle of prism A = 60 ? and refractive index of material of 
prism is 3 . Calculate angle ?.  [2] 
 
 
Q. 10 Why is base band signal not transmitted directly? Give any two reasons. [2] 
 
SECTION – C 
 
Q. 11                [3] 
(i) A screen is placed at a distance of 100 cm from an object. The image of the 
object is formed on the screen by a convex lens for two different locations of the 
lens separated by 20 cm. Calculate the focal length of the lens used. 
(ii) A converging lens is kept coaxially in contact with a diverging lens – both the 
lenses being of equal focal length. What is the focal length of the combination? 
 
Page 3


  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
CBSE 
Class XII Physics 
Board Paper – 2016 
Time: 3 hours                                                                Maximum Marks: 70 
  
General Instructions:                                                                                                                     
(i) All questions are compulsory. There are 26 questions in all. 
(ii) This question paper has five sections: Section A, Section B, Section, Section D 
and Section E. 
(iii) Section A contains five questions of one mark each, section B contains five 
questions of two marks each, section C contains twelve questions of three 
marks each, section D contains one value based question of four marks and 
section E contains three questions of five marks each.  
(iv) There is no overall choice. However, an internal choice has been provided in 
one question of two marks, one question of three marks and all the 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
 
m
e 
= 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
 
 
SECTION – A 
 
Q. 1 A signal of 5 kHz frequency is amplitude modulated on a carrier wave of 
frequency 2 MHz. What are the frequencies of the side bands produced?  [1] 
 
Q. 2 What can be the causes of helical motion of a charged particle??  [1] 
 
Q. 3 Define mobility of a charge carrier. What is its relation with relaxation time?        
                [1] 
 
Q. 4 What is the amount of work done in moving a point charge Q around a circular 
arc of radius ‘r’ at the centre of which another point charge ‘q’ is located? [1] 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
Q. 5 Why can’t we see clearly through fog? Name the phenomenon responsible for 
it. [1] 
 
SECTION – B 
Q. 6 When is H
?
 line in the emission spectrum of hydrogen atom obtained? 
Calculate the frequency of the photon emitted during this transition.  
          
OR 
Calculate the wavelength of radiation emitted when electron in a hydrogen 
atom jumps from n = ? to n = 1.          [2] 
 
Q. 7 When 5 V potential difference is applied across a wire of length 0.1 m, the drift 
speed of electrons is 2.5 ? 10
-4
 m/s. If the electron density in the wire is 8 ? 
10
28
 m
-3
, calculate the resistivity of the material of the wire. [2] 
 
Q. 8 A proton and an ?-particle are accelerated through the same potential 
difference. Which one of the two has (i) greater de-Broglie wavelength, and 
(ii) less kinetic energy? Justify your answer.         [2] 
 
Q. 9 A ray PQ incident on the refracting face BA is refracted in the prism BAC as 
shown in the figure and emerges from the other refracting face AC as RS such 
that AQ = AR. If the angle of prism A = 60 ? and refractive index of material of 
prism is 3 . Calculate angle ?.  [2] 
 
 
Q. 10 Why is base band signal not transmitted directly? Give any two reasons. [2] 
 
SECTION – C 
 
Q. 11                [3] 
(i) A screen is placed at a distance of 100 cm from an object. The image of the 
object is formed on the screen by a convex lens for two different locations of the 
lens separated by 20 cm. Calculate the focal length of the lens used. 
(ii) A converging lens is kept coaxially in contact with a diverging lens – both the 
lenses being of equal focal length. What is the focal length of the combination? 
 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
Q. 12  [3] 
(a) Derive the mathematical expression for law of radioactive decay for a sample of 
a radioactive nucleus. 
(b) How is the mean life of a given radioactive nucleus related to the decay 
constant? 
 
Q. 13 What is space wave propagation? State the factors which limit its range of 
propagation. Derive an expression for the maximum line of sight distance 
between two antennas for space wave propagation.       [3] 
 
Q. 14                       [3] 
(i) Distinguish between a conductor and a semi conductor on the basis of energy 
band diagram. 
(ii) The following figure shows the input waveforms (A, B) and the output waveform 
(Y) of a gate. Identify the gate, write its truth table and draw its logic symbol. 
 
 
 
Q. 15                [3] 
(i) Name two important processes that occur during the formation of a pn junction. 
(ii) Draw the circuit diagram of a full wave rectifier along with the input and output 
waveforms. Briefly explain how the output voltage/current is unidirectional. 
 
Q. 16 State two important properties of photon which are used to write Einstein’s 
photoelectric equation. Define (i) stopping potential and (ii) threshold 
frequency, using Einstein’s equation and drawing necessary plot between 
relevant quantities.  [3] 
 
Q. 17 [3] 
(i) Derive Snell’s law on the basis of Huygen’s wave theory when light is travelling 
from a denser to a rarer medium. 
(ii) Draw the sketches to differentiate between plane wavefront and spherical 
wavefront. 
Page 4


  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
CBSE 
Class XII Physics 
Board Paper – 2016 
Time: 3 hours                                                                Maximum Marks: 70 
  
General Instructions:                                                                                                                     
(i) All questions are compulsory. There are 26 questions in all. 
(ii) This question paper has five sections: Section A, Section B, Section, Section D 
and Section E. 
(iii) Section A contains five questions of one mark each, section B contains five 
questions of two marks each, section C contains twelve questions of three 
marks each, section D contains one value based question of four marks and 
section E contains three questions of five marks each.  
(iv) There is no overall choice. However, an internal choice has been provided in 
one question of two marks, one question of three marks and all the 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
 
m
e 
= 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
 
 
SECTION – A 
 
Q. 1 A signal of 5 kHz frequency is amplitude modulated on a carrier wave of 
frequency 2 MHz. What are the frequencies of the side bands produced?  [1] 
 
Q. 2 What can be the causes of helical motion of a charged particle??  [1] 
 
Q. 3 Define mobility of a charge carrier. What is its relation with relaxation time?        
                [1] 
 
Q. 4 What is the amount of work done in moving a point charge Q around a circular 
arc of radius ‘r’ at the centre of which another point charge ‘q’ is located? [1] 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
Q. 5 Why can’t we see clearly through fog? Name the phenomenon responsible for 
it. [1] 
 
SECTION – B 
Q. 6 When is H
?
 line in the emission spectrum of hydrogen atom obtained? 
Calculate the frequency of the photon emitted during this transition.  
          
OR 
Calculate the wavelength of radiation emitted when electron in a hydrogen 
atom jumps from n = ? to n = 1.          [2] 
 
Q. 7 When 5 V potential difference is applied across a wire of length 0.1 m, the drift 
speed of electrons is 2.5 ? 10
-4
 m/s. If the electron density in the wire is 8 ? 
10
28
 m
-3
, calculate the resistivity of the material of the wire. [2] 
 
Q. 8 A proton and an ?-particle are accelerated through the same potential 
difference. Which one of the two has (i) greater de-Broglie wavelength, and 
(ii) less kinetic energy? Justify your answer.         [2] 
 
Q. 9 A ray PQ incident on the refracting face BA is refracted in the prism BAC as 
shown in the figure and emerges from the other refracting face AC as RS such 
that AQ = AR. If the angle of prism A = 60 ? and refractive index of material of 
prism is 3 . Calculate angle ?.  [2] 
 
 
Q. 10 Why is base band signal not transmitted directly? Give any two reasons. [2] 
 
SECTION – C 
 
Q. 11                [3] 
(i) A screen is placed at a distance of 100 cm from an object. The image of the 
object is formed on the screen by a convex lens for two different locations of the 
lens separated by 20 cm. Calculate the focal length of the lens used. 
(ii) A converging lens is kept coaxially in contact with a diverging lens – both the 
lenses being of equal focal length. What is the focal length of the combination? 
 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
Q. 12  [3] 
(a) Derive the mathematical expression for law of radioactive decay for a sample of 
a radioactive nucleus. 
(b) How is the mean life of a given radioactive nucleus related to the decay 
constant? 
 
Q. 13 What is space wave propagation? State the factors which limit its range of 
propagation. Derive an expression for the maximum line of sight distance 
between two antennas for space wave propagation.       [3] 
 
Q. 14                       [3] 
(i) Distinguish between a conductor and a semi conductor on the basis of energy 
band diagram. 
(ii) The following figure shows the input waveforms (A, B) and the output waveform 
(Y) of a gate. Identify the gate, write its truth table and draw its logic symbol. 
 
 
 
Q. 15                [3] 
(i) Name two important processes that occur during the formation of a pn junction. 
(ii) Draw the circuit diagram of a full wave rectifier along with the input and output 
waveforms. Briefly explain how the output voltage/current is unidirectional. 
 
Q. 16 State two important properties of photon which are used to write Einstein’s 
photoelectric equation. Define (i) stopping potential and (ii) threshold 
frequency, using Einstein’s equation and drawing necessary plot between 
relevant quantities.  [3] 
 
Q. 17 [3] 
(i) Derive Snell’s law on the basis of Huygen’s wave theory when light is travelling 
from a denser to a rarer medium. 
(ii) Draw the sketches to differentiate between plane wavefront and spherical 
wavefront. 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
Q. 18 How are electromagnetic waves produced? What is the source of energy of 
these waves? Write mathematical expressions for electric and magnetic 
fields of an electromagnetic wave propagating along the z-axis. Write any 
two important properties of electromagnetic waves.       [3] 
 
Q. 19                [3] 
(i) When an AC source is connected to an ideal capacitor, show that the average 
power supplied by the source over a complete cycle is zero. 
(ii) A bulb is connected in series with a variable capacitor and an AC source as 
shown. What happens to the brightness of the bulb when the key is plugged in 
and capacitance of the capacitor is gradually reduced? 
 
 
 
Q. 20 State Ampere’s circuital law. Use this law to find magnetic field due to 
straight infinite current carrying wire. How are the magnetic field lines 
different from the electrostatic field lines? 
OR 
State the principle of a cyclotron. Show that the time period of revolution of 
particles in a cyclotron is independent of their speeds. Why is this property 
necessary for the operation of a cyclotron?         [3] 
 
Q. 21 Two identical cells of emf 1.5 V each joined in parallel, supply energy to an 
external circuit consisting of two resistances of 7 ? each joined in parallel. A 
very high resistance voltmeter reads the terminal voltage of cells to be 1.4 
V. Calculate the internal resistance of each cell. [3] 
 
Q. 22 Find the electric field intensity due to a uniformly charged spherical shell at a 
point (i) outside the shell and (ii) inside the shell. Plot the graph of electric 
field with distance from the centre of the shell. [3] 
 
SECTION – D 
 
Q. 23 Seema’s uncle was advised by his doctor to have an MRI (Magnetic 
Resonance Imaging) scan of his brain. Her uncle felt it to be expensive and 
wanted to postpone it. 
When Seema learnt about this, she took the help of her family and also 
approached the doctor, who also offered a substantial discount. She then 
convinced her uncle to undergo the test to enable the doctor to know the 
condition of his brain. The information thus obtained greatly helped the 
doctor to treat him properly. 
Page 5


  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
CBSE 
Class XII Physics 
Board Paper – 2016 
Time: 3 hours                                                                Maximum Marks: 70 
  
General Instructions:                                                                                                                     
(i) All questions are compulsory. There are 26 questions in all. 
(ii) This question paper has five sections: Section A, Section B, Section, Section D 
and Section E. 
(iii) Section A contains five questions of one mark each, section B contains five 
questions of two marks each, section C contains twelve questions of three 
marks each, section D contains one value based question of four marks and 
section E contains three questions of five marks each.  
(iv) There is no overall choice. However, an internal choice has been provided in 
one question of two marks, one question of three marks and all the 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
 
m
e 
= 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
 
 
SECTION – A 
 
Q. 1 A signal of 5 kHz frequency is amplitude modulated on a carrier wave of 
frequency 2 MHz. What are the frequencies of the side bands produced?  [1] 
 
Q. 2 What can be the causes of helical motion of a charged particle??  [1] 
 
Q. 3 Define mobility of a charge carrier. What is its relation with relaxation time?        
                [1] 
 
Q. 4 What is the amount of work done in moving a point charge Q around a circular 
arc of radius ‘r’ at the centre of which another point charge ‘q’ is located? [1] 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
Q. 5 Why can’t we see clearly through fog? Name the phenomenon responsible for 
it. [1] 
 
SECTION – B 
Q. 6 When is H
?
 line in the emission spectrum of hydrogen atom obtained? 
Calculate the frequency of the photon emitted during this transition.  
          
OR 
Calculate the wavelength of radiation emitted when electron in a hydrogen 
atom jumps from n = ? to n = 1.          [2] 
 
Q. 7 When 5 V potential difference is applied across a wire of length 0.1 m, the drift 
speed of electrons is 2.5 ? 10
-4
 m/s. If the electron density in the wire is 8 ? 
10
28
 m
-3
, calculate the resistivity of the material of the wire. [2] 
 
Q. 8 A proton and an ?-particle are accelerated through the same potential 
difference. Which one of the two has (i) greater de-Broglie wavelength, and 
(ii) less kinetic energy? Justify your answer.         [2] 
 
Q. 9 A ray PQ incident on the refracting face BA is refracted in the prism BAC as 
shown in the figure and emerges from the other refracting face AC as RS such 
that AQ = AR. If the angle of prism A = 60 ? and refractive index of material of 
prism is 3 . Calculate angle ?.  [2] 
 
 
Q. 10 Why is base band signal not transmitted directly? Give any two reasons. [2] 
 
SECTION – C 
 
Q. 11                [3] 
(i) A screen is placed at a distance of 100 cm from an object. The image of the 
object is formed on the screen by a convex lens for two different locations of the 
lens separated by 20 cm. Calculate the focal length of the lens used. 
(ii) A converging lens is kept coaxially in contact with a diverging lens – both the 
lenses being of equal focal length. What is the focal length of the combination? 
 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
Q. 12  [3] 
(a) Derive the mathematical expression for law of radioactive decay for a sample of 
a radioactive nucleus. 
(b) How is the mean life of a given radioactive nucleus related to the decay 
constant? 
 
Q. 13 What is space wave propagation? State the factors which limit its range of 
propagation. Derive an expression for the maximum line of sight distance 
between two antennas for space wave propagation.       [3] 
 
Q. 14                       [3] 
(i) Distinguish between a conductor and a semi conductor on the basis of energy 
band diagram. 
(ii) The following figure shows the input waveforms (A, B) and the output waveform 
(Y) of a gate. Identify the gate, write its truth table and draw its logic symbol. 
 
 
 
Q. 15                [3] 
(i) Name two important processes that occur during the formation of a pn junction. 
(ii) Draw the circuit diagram of a full wave rectifier along with the input and output 
waveforms. Briefly explain how the output voltage/current is unidirectional. 
 
Q. 16 State two important properties of photon which are used to write Einstein’s 
photoelectric equation. Define (i) stopping potential and (ii) threshold 
frequency, using Einstein’s equation and drawing necessary plot between 
relevant quantities.  [3] 
 
Q. 17 [3] 
(i) Derive Snell’s law on the basis of Huygen’s wave theory when light is travelling 
from a denser to a rarer medium. 
(ii) Draw the sketches to differentiate between plane wavefront and spherical 
wavefront. 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
Q. 18 How are electromagnetic waves produced? What is the source of energy of 
these waves? Write mathematical expressions for electric and magnetic 
fields of an electromagnetic wave propagating along the z-axis. Write any 
two important properties of electromagnetic waves.       [3] 
 
Q. 19                [3] 
(i) When an AC source is connected to an ideal capacitor, show that the average 
power supplied by the source over a complete cycle is zero. 
(ii) A bulb is connected in series with a variable capacitor and an AC source as 
shown. What happens to the brightness of the bulb when the key is plugged in 
and capacitance of the capacitor is gradually reduced? 
 
 
 
Q. 20 State Ampere’s circuital law. Use this law to find magnetic field due to 
straight infinite current carrying wire. How are the magnetic field lines 
different from the electrostatic field lines? 
OR 
State the principle of a cyclotron. Show that the time period of revolution of 
particles in a cyclotron is independent of their speeds. Why is this property 
necessary for the operation of a cyclotron?         [3] 
 
Q. 21 Two identical cells of emf 1.5 V each joined in parallel, supply energy to an 
external circuit consisting of two resistances of 7 ? each joined in parallel. A 
very high resistance voltmeter reads the terminal voltage of cells to be 1.4 
V. Calculate the internal resistance of each cell. [3] 
 
Q. 22 Find the electric field intensity due to a uniformly charged spherical shell at a 
point (i) outside the shell and (ii) inside the shell. Plot the graph of electric 
field with distance from the centre of the shell. [3] 
 
SECTION – D 
 
Q. 23 Seema’s uncle was advised by his doctor to have an MRI (Magnetic 
Resonance Imaging) scan of his brain. Her uncle felt it to be expensive and 
wanted to postpone it. 
When Seema learnt about this, she took the help of her family and also 
approached the doctor, who also offered a substantial discount. She then 
convinced her uncle to undergo the test to enable the doctor to know the 
condition of his brain. The information thus obtained greatly helped the 
doctor to treat him properly. 
  
 
CBSE XII  | PHYSICS 
Board Paper – 2016 
 
     
Based on the above paragraph, answer the following questions:     [4] 
(a) What according to you are the values displayed by Seema, her family and the 
doctor? 
(b) What could be the possible reason for MRI test to be so expensive? 
(c) Assuming that MRI test was performed using a magnetic field of 0.1 T, find the 
minimum and maximum values of the force that the magnetic field could exert 
on a proton (charge = 1.6 ? 10
-19
 C) moving with a speed of 10
4
 m/s. 
 
SECTION – E 
 
Q. 24                [5] 
(a) When a bar magnet is pushed towards (or away) from the coil connected to a 
galvanometer, the pointer in the galvanometer deflects. Identify the 
phenomenon causing this deflection and write the factors on which the amount 
and direction of the deflection depends. State the laws describing this 
phenomenon. 
(b) Sketch the change in flux, emf and force when a conducting rod PQ of 
resistance R and length l moves freely to and fro between A and C with speed 
v on a rectangular conductor placed in uniform magnetic field as shown in the 
figure. 
 
 
 
OR 
In a series LCR circuit connected to an a.c. source of voltage v = v
m
sin?t, use 
phasor diagram to derive an expression for the current in the circuit. Hence, obtain 
the expression for the power dissipated in the circuit. Show that power dissipated at 
resonance is maximum.  [5] 
 
Q. 25                [5] 
(a) Why does unpolarised light from a source show a variation in intensity when 
viewed through a polaroid which is rotated? Show with the help of a diagram, 
how unpolarised light from Sun gets linearly polarised by scattering. 
(b) Three identical polaroid sheets P
1
, P
2
 and P
3
 are oriented so that the pass axis 
of P
2
 and P
3
 are inclined at angles of 60 ? and 90 ? respectively with the pass axis 
of P
1
. A monochromatic source S of unpolarised light of intensity I
0
 is kept in 
front of the polaroid sheet P
1
 as shown in the figure. Determine the intensities