# Sample Paper Class 12 Physics Term 1 Set B

Please refer to Sample Paper Class 12 Physics Term 1 Set B with solutions provided below. We have provided CBSE Sample Papers for Class 12 Physics as per the latest paper pattern and examination guidelines for Standard 12 Physics issued by CBSE for the current academic year. The below provided Sample Guess paper will help you to practice and understand what type of questions can be expected in the Class 12 Physics exam.

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

Section – A

This section consists of 25 multiple choice questions with overall choice to attempt any 20 questions. In case more than desirable number of questions are attempted, ONLY first 20 will be considered for evaluation.

Q. 1. For alternating current magnitude of r.m.s. value is
(A) Greater than peak value
(B) Smaller than peak value
(C) Equal to peak value
(D) No way related with peak value

B

Q. 2. In an a.c. circuit, average power supplied to an inductor over one complete cycle is
(A) 0
(B) ∞
(C) Depends on the value of inductance
(D) Depends on the value of angular frequency

A

Q. 3. In an a.c. circuit when the capacitor is fully charged, the current in the circuit
(A) Maximum
(B) Minimum but not zero
(C) Zero
(D) Depends on the capacitance value

C

Q. 4. In a LCR series ac circuit, the voltage across each of the component L,C and R is 120 V. The voltage across the LC combination will be
(A) 120 V
(B) 60 V
(C) 240 V
(D) 0 V

D

Q. 5. LC oscillations is not realistic
(A) since every inductor has some resistance.
(B) Energy is radiated away from the system in the form of electromagnetic waves
(C) Both (A) and (B)
(D) Neither (A) nor (B)

C

Q. 6. In actual transformers, which of the followings does not cause energy loss?
(A) Flux leakage
(B) Eddy current
(C) Mutual induction
(D) Winding resistance

C

Q. 7. A charge Q is enclosed by a Gaussian spherical surface of radius R. If the radius is doubled then the outward electrical flux will
(A) Remains same
(B) Increase 4 times
(C) Reduced to half
(D) Be doubled

C

Q. 8. The electric potential V at any point (x, y, z) in space is given by V = 4x2 volt. The electric field at the point (1, 0, 2) is
(A) 16 V/m along positive X-axis
(B) 16 V/m along negative X-axis
(C) 8 V/m along positive X-axis
(D) 8 V/m along negative X-axis

D

Q. 9. A electric dipole of moment p is placed in an electric field of intensity E. The dipole acquires a position such that the axis of the dipole makes an angle θ with the direction of the field. Assuming that the potential energy of the dipole t be zero when θ = 90°, the torque and the potential energy of the dipole will be respectively
(A) pE cos θ, –pE sin θ
(B) pE sin q, pE cos q
(C) pE sin q, –pE cos θ
(D) pE sin θ, –pE cos θ

D

Q. 10. Which of the following graphs represents he variation of resistivity with temperature for a metal?

B

Q. 11. When a cell is connected to a 2 Ω resistor, 0.9 A current flows. If the same cell is connected to 7 Ω resistor, 0.3 A current flows. The internal resistance of the cell is
(A) 1 Ω
(B) 0.5 Ω
(C) 1.5 Ω
(D) 0.05 Ω

B

Q. 12. The amount of electric charge passing through a cross-section of wire in time t is
Q(t) = at2 + bt
where a and b are constants having value 3 and 4 respectively. Calculate the value of electric current at t = 4 seconds.
(A) 27 A
(B) 28 A
(C) 29 A
(D) 30 A

B

Q. 13. When short-circuited, the terminal potential difference of a cell of e.m.f. E is
(A) 0
(B) E
(C) E/2
(D) E/2

A

Q. 14. When cells are connected in parallel
(A) e.m.f. increases
(B) e.m.f. decreases
(C) Current decreases
(D) Current increases

D

Q. 15. A wire loop is rotated in a magnetic field. The frequency of change in direction of induced e.m.f. is
(A) 4
(B) 2
(C) 1
(D) 0

B

Q. 16. The capacity of parallel plate condenser depends on :
(A) The type of metal used
(B) The thickness of plates
(C) The potential applied across the plates
(D) The separation between the plates

D

Q. 17. The energy stored in a condenser of capacity C which has been raised to a potential V is given by :
(A) (1/2)CV
(B) (1/2)CV2
(C) CV
(D) (1/2)VC

B

Q. 18. The capacity of a parallel plate condenser is C. Its capacity when the separation between the plates is halved will be :
(A) 4C
(B) 2C
(C) C/2
(D) C/4

B

Q. 19. Three capacitors of capacitances 3μF, 9μF and 18μF are connected once in series and another time in parallel. The ratio of equivalent capacitance in the two cases (Cs/CP) will be :
(A) 1 : 15
(B) 15 : 1
(C) 1 : 1
(D) 1 : 3

A

Q. 20. From the graph between current I & voltage V shown, identify the portion corresponding to negative resistance :

(A) DE
(B) CD
(C) BC
(D) AB

B

Q. 21. The internal resistance of a cell of emf 2V is 0.1 Ω. It’s connected to a resistance of 3.9 Ω. The voltage across the cell will be :
(A) 0.5 volt
(B) 1.9 volt
(C) 1.95 volt
(D) 2 volt

C

Q. 22. The resistance of an ideal voltmeter is :
(A) Zero
(B) Very low
(C) Very large
(D) Infinite

D

Q. 23. The magnetic field at a distance R from a long wire carrying current I is 0.4 Tesla. The magnetic field at a distance 2R is :
(A) 0.2 Tesla
(B) 0.8 Tesla
(C) 0.1 Tesla
(D) 1.6 Tesla

A

Q. 24. In an ac circuit of capacitance, the current from potential is :
(A) Forward
(B) Backward
(C) Both are in the same phase
(D) None of these

A

Q. 25. In an a.c. circuit the e.m.f. (E) and the current (I) at any instant are given respectively by E = E0 sinωT, I = I0 sin(ωT − ϕ). The average power in the circuit over one cycle of a.c. is :
(A) E0I0 (B) E0I0/2
(C) (E0I0/2) sin ϕ
(D) (E0I0/2) cos ϕ

D

Section – B

This section consists of 24 multiple choice questions with overall choice to attempt any 20 questions. In case more than desirable number of questions are attempted, ONLY first 20 will be considered for evaluation.

Q. 26. In the given figure shows point charges + 4q, –2q and –q. Two charges are enclosed within the surface S. What is the electric flux due to configuration through the surface S?

(A) ϕ = 2q/ε0
(B) ϕ = q/ε0
(C) ϕ = –q/ε0
(D) ϕ

A

Q. 27. A point charge +q, is placed at a distance D from an isolated conducting plane. The field at a point P on the other side of the plane is
(A) directed perpendicular to the plane and away from the plane.
(B) directed perpendicular to the plane but towards the plane.
(C) directed radially away from the point charge.
(D) directed radially towards the point charge.

A

Q. 28. A hemisphere is uniformly charged positively. The electric field at a point on a diameter away from the centre is directed
(A) perpendicular to the diameter.
(B) parallel to the diameter.
(C) at an angle tilted towards the diameter.
(D) at an angle tilted away from the diameter.

A

Q. 29. Five charges q1, q2, q3, q4, and q5 are fixed at their positions as shown in Figure. S is a Gaussian surface. The Gauss’s law is given by:

Which of the following statements is correct?

(A) E on the LHS of the above equation will have a contribution from q1, q5 and q3 while q on the RHS will have a contribution from q2 and q4 only.
(B) E on the LHS of the above equation will have a contribution from all charges while q on the RHS will have a contribution from q2 and q4 only.
(C) E on the LHS of the above equation will have a contribution from all charges while q on the RHS will have a contribution from q1, q3 and q5 only.
(D) Both E on the LHS and q on the RHS will have contributions from q2 and q4 only.

B

Q. 30. What is the value of potential inside a hollow spherical charged conductor
(A) Constant
(B) Same as on its surface
(C) Both (A) and (B)
(D) None of the above

A

Q. 31. A positively charged particle is released from rest in an uniform electric field. The electric potential energy of the charge
(A) remains a constant because the electric field is uniform.
(B) increases because the charge moves along the electric field.
(C) decreases because the charge moves along the electric field.
(D) decreases because the charge moves opposite to the electric field.

C

Q. 32. Calculate the amount of work done in turning an electric dipole of dipole moment 4 × 10-6 cm from its position of unstable equilibrium to the position of stable equilibrium, in a uniform electric field of intensity 10-2 NC-1.
(A) – (4 × 10-8) J
(B) – (8 × 10-8) J
(C) (8 × 10-8) J
(D) (4 × 10-8) J

C

Q. 33. Two cells of EMFs 1 volt and 1.5 volt having internal resistance of 0.1 W and 0.2 W respectively are connected in parallel. Calculate the EMF and the internal resistance of the equivalent cells.
(A) 1.17 V
(B) 1.20 V
(C) 1.10 V
(D) 1.00 V

A

Q. 34. 7 drops each having the capacity C and potential V are combined to form a big drop. If the charge on the small drop is q, then the net charge on the big drop will be
(A) 3.5q
(B) 7q
(C) 14q
(D) 4q

B

Q. 35. When an electron is projected along the axis of the same circular conductor carrying the same current. Electron will experience.
(A) A force along the axis
(B) No force experienced
(C) A force perpendicular to the axis
(D) None of these

B

Q. 36. Two batteries of emf ε1 and ε22 > ε1) and internal resistances r1 and r2 respectively are connected in parallel as shown in figure :

(A) The equivalent emf εeq of the two cells is between ε1 and ε2, i.e. ε1 < εeq < ε2.
(B) The equivalent emf εeq is smaller than ε1.
(C) The εeq is given by εeq = ε1 + ε2 always.
(D) εeq is independent of internal resistances r1 and r2.

A

Q. 37. A resistance R is to be measured using a meter bridge. Student chooses the standard resistance S to be 100 Ω. He finds the null point at l1 = 2.9 cm. He is told to attempt to improve the accuracy. Which of the following is a useful way?
(A) He should measure l1 more accurately.
(B) He should change S to 1000 Ω and repeat the experiment.
(C) He should change S to 3 Ω and repeat the experiment.
(D) He should give up hope of a more accurate measurement with a meter bridge.

C

Q. 38. Two resistances are connected in two gaps of Meter Bridge. The balance is 10 cm from the zero end. A resistance of 20 Ω is connected in series with the smaller of the two. The null point shifts to 20 cm. What is the value of the bigger resistance?
(A) 89 Ω
(B) 144 Ω
(C) 100 Ω
(D) None of the above

B

Q. 39. A current carrying circular loop of radius R is placed in the x-y plane with centre at the origin. Half of the loop with x > 0 is now bent so that it now lies in the y-z plane.
(A) The magnitude of magnetic moment now diminishes.
(B) The magnetic moment does not change.
(C) The magnitude of B at (0,0,z), z >>R increases.
(D) The magnitude of B at (0,0,z), z >>R is unchanged.

A

Q. 40. A magnetic needle lying parallel to the magnetic field requires w unit of work to turn it through 60°. Find the value of torque needed to maintain the needle in this position.
(A) W (√3 /2)
(B) W/2
(C) W √3
(D) 3W/2

C

Q. 41. An electron is projected with uniform velocity along the axis of a current carrying long solenoid. Which of the following is true?
(A) The electron will be accelerated along the axis.
(B) The electron path will be circular about the axis.
(C) The electron will experience a force at 45° to the axis and hence execute a helical path.
(D) The electron will continue to move with uniform velocity along the axis of the solenoid.

D

Q. 42. Consider the two idealized systems : (i) a parallel plate capacitor with large plates and small separation and (ii) a long solenoid of length L >> R, radius of cross-section. In (i) E is ideally treated as a constant between plates and zero outside. In (ii) magnetic field is constant inside the solenoid and zero outside. These idealized assumptions, however, contradict fundamental laws as below :
(A) case (i) contradicts Gauss’s law for electrostatic fields.
(B) case (ii) contradicts Gauss’s law for magnetic fields.
(C) case (i) agrees with ϕ s E.dl = 0
(D) case (ii) contradicts ϕ H.dl = Ien

B

Q. 43. The magnetic field of Earth can be modelled by that of a point dipole placed at the centre of the Earth. The dipole axis makes an angle of 11.3° with the axis of Earth. At Mumbai, declination is nearly zero. Then,
(A) the declination varies between 11.3° W to 11.3° E.
(B) the least declination is 0°.
(C) the plane defined by dipole axis and Earth axis passes through Greenwich.
(D) declination averaged over Earth must be always negative.

A

Q. 44. Consider a metre bridge whose length of wire is 2 m. A resistance of 10 W is connected across one gap of the meter bridge and an unknown resistance is connected across the other gap. When the resistances are interchanged, the balance point shifts by 50 cm. What is the value of the unknown resistance?
(A) 250 W
(B) 10 W
(C) 16.7 W
(D) None of the above

C

Given below are two statements labelled as Assertion (A) and Reason (R)

Directions: In the following questions, a statement of Assertion (A) and is followed by a statement of Reason (R). Mark the correct choice as:
(A) Both Assertion (A) and Reason (R) are true, and Reason(R) is the correct explanation of (A).
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
(C) Assertion (A) is true, but Reason (R) is false.
(D) Assertion (A) is false, but Reason (R) is true.

Q. 45. Assertion (A): Magnetic field interacts with a moving charge only.
Reason (R): Moving charge produces a magnetic field.

A

Q. 46. Assertion (A): Compass needle points the magnetic north-south direction.
Reason (R): The magnetic meridian of the earth merges with the axis of rotation of earth.

C

Q. 47. Assertion (A): When two identical loops of copper and aluminium are rotated with same speed in the same magnetic field, the induced e.m.f. will be same.
Reason (R): Resistance of the two loops are equal.

C

Q. 48. Assertion (A): Mutual inductance becomes maximum when coils are wound on each other.
Reason (R): Mutual inductance is independent of orientation of coils.

C

Q. 49. Assertion (A): Both ac and dc can be measured by hot wire instrument.
Reason (R): Hot wire instrument is based on the principal of magnetic effect of current.

C

Section – C

This section consists of 6 multiple choice questions with an overall choice to attempt any 5. In case more than desirable number of questions are attempted, ONLY first 5 will be considered for evaluation.

Q. 50. The equivalent capacitance between A and B in the given combination of 5 capacitors (each 2μF) is

(A) 7/6 μF
(B) 6/7 μF
(C) 10 μF
(D) 2 μF

B

Q. 51. Current drawn from the battery by the network of resistors is

(A) 2A
(B) 0.5A
(C) 4A
(D) 0

A

CASE STUDY

Read the following text and answer the following questions on the basis of the same:

Losses of transformer
There are 4 types of losses in a transformer: Core loss, Ohmic loss, Stray load loss and dielectric loss.
(1) Core loss
Core loss has two components – hysteresis loss and eddy current loss. These together are called no-load losses of a transformer and are calculated by open circuit test.
(A) Hysteresis loss: This loss mainly depends on the core material used in the transformer. To reduce this loss, the high-grade core material can be used. CRGO- Cold rolled grain oriented Si steel is commonly used for this purpose.
(B) Eddy current loss: This loss can be reduced by designing the core using slight laminations.
These losses are present even when no load is connected. So, these are also known as no-load loss.
(2) Copper Loss
Copper losses occur because of the Ohmic resistance in the windings of the transformer. If the currents in primary and secondary windings of the transformer are I1 and I2, and if the resistances of these windings are R1 & R2 then the copper losses that occurred in the windings are I1 2R1 & I2 2R2 respectively. So, the entire copper loss will be I1 2R1 + I2 2R2.
This loss is also called variable or ohmic losses because this loss changes based on the load.
(3) Stray Loss
These types of losses in a transformer occur because of the occurrence of the leakage flux. As compared with copper and iron losses, the percentage of stray losses are less, so these losses can be neglected.
(4) Dielectric Loss
This loss mainly occurs within the oil of the transformer. Oil is an insulating material. Once the oil quality in the transformer deteriorates then the transformer’s efficiency is affected.
Efficiency of Transformer
It is the ratio of output power and input power.
Efficiency = Output Power / Input Power.
The transformer is a highly efficient device which ranges between 95% – 98.5%.

Q. 52. What is the relationship among core loss, hysteresis loss and eddy current loss?
(A) Eddy current loss = Core loss + Hysteresis loss
(B) Core loss = Hysteresis loss + eddy current loss
(C) Hysteresis loss = Core loss + eddy current loss
(D) Core loss = Hysteresis loss X eddy current loss

B

Q. 53. Which of the following losses in transformer is also known as no-load loss?
(A) Copper loss
(B) Stray loss
(C) Dielectric loss
(D) Core loss

D

Q. 54. Which of the following losses in transformer is also known as variable loss?
(A) Copper loss
(B) Stray loss
(C) Dielectric loss
(D) Core loss

A

Q. 55. How hysteresis loss can be reduced?
(A) Using core of Si Steel
(B) Using laminated core
(C) Using core of non-ferromagnetic material
(D) Using oil of higher dielectric constant