# Unseen Passage

For Class 4 to Class 12

# Class 12 Physics Sample Paper Term 1 Set D

Please see below Class 12 Physics Sample Paper Term 1 Set D with solutions. We have provided Class 12 Physics Sample Papers with solutions designed by Physics teachers for Class 12 based on the latest examination pattern issued by CBSE. We have provided the following sample paper for Term 1 Class 12 Physics with answers. You will be able to understand the type of questions which can come in the upcoming exams.

## CBSE Sample Paper for Class 12 Physics Term 1 Set D

Section A

Question 1. Two equal unlike charges placed 3 cm apart in air attract each other with a force of 40 N.
The magnitude of each charge in micro coulombs is:
a) 20000
b) 2
c) 200
d) 20

B

Question 2. The effective capacitance of two capacitors of capacitances C1 and C2 (with C2 > C1) connected in parallel is 25/6 times the effective capacitance when they are connected in series. The ratio C2/C1 is
a) 25/6
b) 5/3
c) 4/3
d) 3/2

D

Question 3. A potentiometer wire, 10 m long, has resistance 40 ohms. It is put in series with a resistance 760 ohms and connected to a 2 volt battery. The potential gradient in the wire is:
a) 1× 10−6volt/m
b) 1× 10−2volt/m
c) 1× 10−4volt/m
d) 1× 10−3volt/m

B

Question 4. A conducting sphere of radius 10 cm has an unknown charge. If the electric field 20 cm from the centre of the sphere is 1. 5× 103N/C and points radially inward, what is the net charge on the sphere?
a) 6.67 nC
b) 7.67 nC
c) 7.27 nC
d) -6.27 nC

A

Question 5. Two identical capacitors, have the same capacitance C. One of them is charged to potential Vand the other to V2 . The negative ends of the capacitors are connected together. When the positive ends are also connected, the decrease in energy of the combined system is –
a) 1/4 (V1 − V2) 2
b) 1/4 (V12 + V22
c) 1/4 (V12 − V22
d) 1/4 (V1 + V2) 2

A

Question 6. If the percentage change in current through a resistor is 1%, then the change in power through it would be:
a) 0.5%
b) 1%
c) 2%
d) 1.7%

C

Question 7. Eddy currents are produced in
a) Induction furnace
b) All of these
c) Speedometer
d) Electromagnetic brakes

B

Question 8. A bar magnet of length 3 cm has points A and B along its axis at distances of 24 cm and 48 cm on the opposite sides. Ratio of magnetic fields at these points will be

a) 1/2
b) 4
c) 3
d) 8

D

Question 9. If number of turns per unit length of a coil of a solenoid is doubled, its self-inductance will
a) be doubled
b) be halved
c) remain constant
d) be four times

D

Question 10. The core of any transformer is laminated, so as to:
a) reduce the energy loss due to eddy currents
b) increase the secondary voltage
c) make it robust and strong
d) make it light weight

A

Question 11. An electron is moving in a circular path under the influence of a transverse magnetic field of 3.57 × 10-2 T. If the value of e/m is 1.76×1011 C/kg, the frequency of revolution of the electron is
a) 6.28 MHz
b) 62.8 MHz
c) 100 MHz
d) 1 GHz

A

Question 12. Si and Cu are cooled from 300 K to a temperature of 60 K. Then resistivity:
a) decreases for both Si and Cu
b) increases for both Si and Cu
c) for Cu increases and for Si decreases
d) for Si increases and for Cu decreases

D

Question 13. There are two coils A and B as shown in Figure. A current starts flowing in B as shown when A is moved towards B and stops when A stops moving. The current in A is counterclockwise. B is kept stationary when A moves. We can infer that

a) there is a constant current in the counterclockwise direction in A
b) there is a constant current in the clockwise direction in A
c) there is no current in A
d) there is a varying current in A

A

Question 14. A series circuit consists of an ac source of variable frequency, a 115.0 Ω resistor, a 1.25 μF capacitor, and a 4.50-mH inductor. The impedance of this circuit when the angular frequency of the ac source is adjusted to half the resonant angular frequency is
a) 156.0 Ω
b) 166.0 Ω
c) 176.0 Ω
d) 146.0 Ω

D

Question 15. Three charged particles are collinear and are in equilibrium, then
a) the equilibrium is unstable
b) all the charged particles have the same polarity
c) all the charged particles cannot have the same polarity
d) the equilibrium is unstable and all the charged particles cannot have the same polarity

D

Question 16. A spherical drop of capacitance 1 F is broken into eight drops of equal radius. Then, the capacitance of each small drop is
a) 1/4 μF
b) 1/2 μF
c) 8 F
d) 1/8 μF

B

Question 17. A magnet of magnetic moment 2JT-1 is aligned in the direction of magnetic field of 0.1.T.What is the net work done to bring the magnet normal to the magnetic field?
a) 0.2J
b) 2J
c) 0.1J
d) 10-2J

A

Question 18. A coil has a resistance of 48.0 . At a frequency of 80.0 Hz, the voltage across the coil leads the current in it by 530. Inductance of the coil is
a) 0.124 H
b) 0.94 H
c) 0.114 H
d) 0.84 H

A

Question 19. A charged particle (charge q) is moving in a circle of radius R with uniform speed v. The associated magnetic moment p is given by:
a) (qvR)/2
b) qvR
c) qvR2
d)(qvR2)/2

A

Question 20. The amount of charge a capacitor can store when a potential diffrence of 1V is applied across it is called its
a) resistance
b) capacitance
c) reactance
d) inductance

B

Question 21. A point charge of 2.0μC is at the centre of a cubic gaussian surface 9.0 cm on edge. What is the net electric flux through the surface?
a) 2. 5× 105Nm2/C
b) 3. 1× 105Nm2/C
c) 2. 26× 105Nm2/C
d) 1. 7× 105Nm2/C

C

Question 22. A series resonant LCR circuit has a quality factor (Q-factor) 0.4. If R = 2 kΩ , C = 0.1 μF, then the value of inductance is
a) 0.064 H
b) 0.1 H
c) 5 H
d) 2 H

A

Question 23. When the current changers from + 2 A to – 2 A in 0 ⋅ 05s , an e.m.f. of 8 V is induced in the coil. The coefficient of self-induction of the coil is:
a) 0 ⋅ 2 H
b) 0 ⋅ 1 H
c) 0 ⋅ 4 H
d)  0 ⋅ 8 H

B

Question 24. The materials suitable for making electromagnets should have
a) low retentivity and high coercivity
b) high retentivity and high coercivity
c) high retentivity and low coercivity
d) low retentivity and low coercivity

D

Question 25. Two long parallel wires P and Q are held perpendicular to the plane of the paper with distance of 5 m between them. If P and Q carry current of 2.5 A and 5A respectively in the same direction, then the magnetic field at a point half way between the wire is

D

Section B

Question 26. In the given figure, the loop is fixed but the straight wire can move. The straight wire will:

b) move towards the loop
c) remain stationary
d) move away from the loop

B

Question 27. If potential (in volts) in a region is expressed as V(x, y, z) = 6xy – y + 2yz, the electric field (in N/C) at point (1, 1, 0) is:

C

Question 28. A half ring of radius R has a charge per unit length equal to λ. The field at the center is
a) zero
b) 2λ/4πε0R
c) λ/4πε0R
d) None of these

B

Question 29. A coil has resistance 30 ohm and inductive reactance 20 ohm at 50 Hz frequency. If an ac source of 200 volt, 100 Hz, is connected across the coil, the current in the coil will be:
a) 2.0 A
b) 4.0 A
c) 20√13 A
d) 8.0 A

B

Question 30. Which of the following quantities remain constant in a step down transformer?
a) Current
b) None of these
c) Power
d) Voltage

C

Question 31. A closely wound solenoid of 800 turns and area of cross section 2. 5× 10−4m2 carries a current of 3.0 A. What is its associated magnetic moment?
a) 0.4 J/T
b) 0.8 J/T
c) 0.6 J/T
d) 0.5 J/T

C

Question 32. A moving conductor coil produces an induced emf. This is in accordance with:
a) Lenz’s law
b) Coulomb’s law
c) Ampere’s law

D

33. In the circuit shown, the current through the 5Ω resistor is:

a) 8/3 A
b) 4/13 A
c) 9/13 A
d) 1/3 A

D

Question 34. An electric charge 10-3μ C is placed at the origin (0, 0) of the (x-y) coordinate system. Two points A and B are situated at (√2,√2) and (2, 0) respectively. The potential difference between points A and B will be
a) zero
b) 9 volt
c) 4.5 volt
d) 2 volt

A

Question 35. Three copper wires have lengths and cross-sectional areas as (l, A); (2l,A/2 ) and (1/2 , 2 A).
Resistance is minimum in:
a) same in all the three cases
b) wire of cross-sectional area A
c) wire of cross-sectional area A/2
d) wire of cross-sectional area 2 A

D

Question 36. The phase difference between the current and voltage at resonance is
a) 0
b) −π
c) π
d) π/2

A

Question 37. An aeroplane having a wingspan of 35m files due north with the speed of 90 m/s, given B = 4×10-5 T. The potential difference between the tips of the wings will be
a) 0.126 V
b) 1.26 V
c) 0.013 V
d) 12.6 V

A

Question 38. In the magnetic meridian of a certain place, the horizontal component of the earth’s magnetic field is 0.26 G and the dip angle is 60o. What is the magnetic field of the earth at this location?
a) 0.52 G
b) 0.58 G
c) 0.65 G
d) 0.62 G

A

Question 39. If the resistance of 100 , the inductance of 0.5 H, and capacitance of 10×10-6 F are connected in series through 50 Hertz AC supply, the impedance will be:
a) 18.7 Ω
b) 189.7 Ω
c) 101.3 Ω
d) 1.87 Ω

B

Question 40. One kilowatt-hour is equal to:
a) 36 × 105 J
b) 36 × 10-5 J
c) 36 × 103 J
d) 36 × 10-3 J

A

Question 41. The equivalent resistance of two resistances P and Q which are in series is

D

Question 42. A charged oil drop is suspended in uniform field of 3 × 104 V m-1 so that it neither falls nor rises. The charge on the drop will be : (take the mass of the charge 9.9 10-15 kg and g =10 ms-2)
a) 3 ⋅ 3× 10−18 C
b) 4 ⋅ 8× 10−18 C
c) 1 ⋅ 6× 10−18 C
d) 4 ⋅ 3× 10−18 C

A

Question 43. The resistance of a galvanometer is 50Ω and the current required to give full scale deflection is 100μA  . In order to convert it into an ammeter for reading up to 10 A, it is necessary to put a resistance of
a) 5× 10−2Ω
b) 5× 10−5Ω
c) 5× 10−4 Ω
d) 5× 10−3Ω

C

Question 44. The best material for the core of a transformer is
a) soft iron
b) hard steel
c) mild steel
d) stainless steel

A

Question 45. Assertion (A): Two adjacent conductors of unequal dimensions, carrying the same positive charge have a potential difference between them.
Reason (R): The potential of a conductor depends upon the charge given to it.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.

B

Question 46. Assertion (A): Magnetic susceptibility is a pure number.
Reason (R): The value of magnetic susceptibility for vacuum is one.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.

C

Question 47. Assertion (A): An induced emf appears in any coil in which the current is changing.
Reason(R): Self-induction phenomenon obeys Faraday’s law of induction.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.

B

Question 48. Assertion (A): When capacitive reactance is smaller than the inductive reactance in LCR current, e.m.f. leads the current.
Reason (R): The phase angle is the angle between the alternating e.m.f. and alternating current of the circuit.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.

B

Question 49. Assertion (A): In a cavity within a conductor, the electric field is zero.
Reason (R): Charges in a conductor reside only at its surface.
a) Both A and R are true and R is the correct explanation of A.
b) Both A and R are true but R is not the correct explanation of A.
c) A is true but R is false.
d) A is false but R is true.

A

Section C

Question 50. Two charges -10C and +10C are placed 10 cm apart. Potential at the centre of the line joining the two charges is:
a) 4 V
b) zero
c) -2 V
d) 2 V

B

Question 51. Two charged spheres separated at a distance d exert a force F on each other. If they are immersed in a liquid of dielectric constant 2, then the force (if all conditions are same) is
a) F/2
b) 4F
c) F
d) 2F

A

Question No. 52 to 55 are based on the given text. Read the text carefully and answer the questions:

The potentiometer consists of a long resistive wire(L) and a battery of known EMF, V whose voltage is known as driver cell voltage. Assume a primary circuit arrangement by connecting the two ends of L to the battery terminals. One end of the primary circuit is connected to the cell whose EMF E is to be measured and the other end is connected to galvanometer G. This circuit is assumed to be a secondary circuit.

Question 52. How can we increase the sensitivity of a potentiometer?
a) Decreasing the length of potentiometer wire
d) Increasing resistance put in parallel

B

Question 53. If l1 and l2 are the balancing lengths of the potentiometer wire for the cells of EMFs ε1 and ε2, then
a) None of these
b) ε1 ε= l1l2
c) ε1/ ε= l1/l2
d) ε12 = l1 + l2

C

Question 54. Example of a potentiometer is
a) Joystick
b) All of these
c) Mobile
d) Modem

A

Question 55. The emf of a cell is always greater than its terminal voltage. Why?
a) Because there is some potential drop across the cell due to its high current
b) Because there is some potential drop across the cell due to its small internal resistance
c) Because there is some potential drop across the cell due to its large internal resistance
d) Because there is some potential drop across the cell due to its low current