MCQ Based Sample Paper Physics Term 1 for Class 12 2021-22
1. If an electron is moving with velocity produces a magnetic field B”, then
a) the direction of field B will be same as the direction of velocity v
b) the direction of field B’ will be opposite to the direction of velocity v’.
c) the direction of field B will be perpendicular to the direction of velocity v.
d) the direction of field B’ does not depend upon the direction of velocity v
2. The current sensibility of a moving coil galvanometer increases with decrease in:
a) magnetic field
b) area of coil
c) number of turns
d) None of these
3. What is the angle of dip at the magnetic
a) 30°
b) 0°
c) 45°
d) None of these
4. Three charges + 3q+q and Q are placed on a st. line with equal separation. In order to maket the net force on q to be zero, the value of Q will be:
a) +3q
b) +2q
c)-3q
d) -4q
5. The coupling co-efficient of the perfectly coupled coils is:
a) Zero
b) 1
c) slightly more than 1
d) infinite
6. In a uniform magnetic field B, a wire in the form of a semicircle of radius r rotated about the diameter of the circle with angular frequency ‘ω’ . The axis of rotation is perpendicular to the field. If the total resistance of the circuit is R the mean power generated per period of rotation is:
a) Bπ r2ω/2R
b) (Bπ r2ω)2/8R
c) (Bπrω)2/2R
d) (Bπ rω2)2/8R
7. A metal conductor of length 1 m rotates vertically about one of its ends at angular velocity 5 rad s-1. If the horizontal component of earth’s magnetism is 2 x 10-5 T. then e.m.f. developed between the two ends of the conductor is:
a) 5 µV
b) 50 µV
c) 5 mV
d) 50 mV
8. Dielectric strength of a medium is 2 KV mm-1. What is the maximum potential difference that can be set up across a 50 μm specimen without puncturing it.
a) 10 V
b) 100 V
c) 1000 V
d) 10,000 V
9. Three capacitors of capacitances 3μF, 9μF and 18 μF are connected once in series and then in parallel. The ratio of equivalent capacitances Cs, Cp will be:
a) 1:15
b) 15:1
c) 1:1
d) 1:3
10. The work done in moving the three charges to infinite separation is:
a) 180 ergs
b) 60 ergs
c)-60 ergs
d) (20+15-12) ergs
11- Which of the following materials can be used to make a Faraday cage
a) Plastic
b) Glass
c) Copper
d) Wood
12. An electric dipole is placed at an angle of 30° to a non-uniform electric field. The dipole will experience
a) torque only
b) a translational force only in the direction of the field
c) a translational force only in a direction normal to the direction of the field
d) a torque as well as a translational force
13. The permeability of a paramagnetic substance is
a) very large
b) small but more than unity
c) less than unity
d) negative
14. According to Ampere’s Circuital law
a) ∮ B x dt=0
b) ∮ B.dl= μ0l
c) ∮Bx dl=0
d) ∮ B.dl=μ0l/4π
15. Which of the following is blocked by a capacitor?
a) A.C.
b) D.C.
c) Both A.C. and D.C.
d) Neither A.C. nor D. C
16. The amount of work required to increase the distance between -6μC and 4μC from 6 cm to 18 cm will be
a) 1.8 J
b) 2.4 J
c) 1.8 μJ
d) 2.4 μJ
17. A bird sitting on a high-power line:
a) gets killed instantly
b) gets a mild shock
c) gets a fatal shock
d) is not affected practically
18. In the following figure represents a balanced Wheatstone bridge circuit. What is the value of X?
figure
a) 15 Ω
b) 20 Ω
c) 25 Ω
d) 30Ω
19. Two identical bar magnets each of dipole moment p and length I are perpendicular to each other as shown in Fig. The dipole moment of the combination is:
figure
a) √2 p
b) p√2
c) P
d) 2p
20. The strength of magnetic field at the centre of circular coil is
figure
a)
b)
c)
d)
21. Current flows through uniform, square frames as shown in the figure. In which case is the magnetic field at the centre of the frame not zero?
a)
b)
c)
d)
22. The correct plot of the magnitude of magnetic field Vector B versus distance r from centre of the wire is, if the radius of wire is R
a)
b)
c)
d)
23. The vertical component of earth’s magnetic field. at a place is √3 times the horizontal component the value of angle of dip at this place is
a) 30°
b) 45°
c) 60°
d)90°
24. In the given figure current from A to B in the straight wire is decreasing. The direction of induced current in the loop is A
a) clockwise
b) anticlockwise
c) changing
d) nothing can be said
25. Faraday’s laws are consequence of the conservation of
a) charge
b) energy
c) magnetic field
d) both b) and c)
Question no 26 to 30 of assertion reasons
a) Both assertion A and Reason are true and Reason R is the correct explanation of assertion A
b) Both assertion (A) and the 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) ir false and Reason (R) is also false
26. Assertion (A): in water, value of magnetic field decreases
Reason R) water is a diamagnatic substance
27. Assertion (A) Gauss’s law of magnetism is different from that for electrostatics
Reason (R) isolated magnetic poles are not known to exist
28. Assertion(A) electric potential of the ear h is zero.
Reason (R) the electric field due to the earth is zero
29. Assertion (A) in a simple battery circuit the paint of lowest potential is positive terminal of the battery.
Reason (R) the current flows towards the point of the higher potential as it flows in such a circuit from the negative to the positive terminal.
30. Assertion(A):some electric appliances have three pins, even though, if we remove the top pin, it will continue working
Reason (R): the third pin is used only as a safety device
Read the case given below and answer the questions on the basis of the same
Current can be induced not only in conducting coils, but also in conducting sheets or blocks current is induced in solid metallic masses when the magnetic flux threading through them charges, such currents flow in the form of irregularly shaped loops throughout the body of the metal, these currents look like Eddie’s or wire pools in water so they are known as eddy currents, Eddy currents have both undesirable effects and practically useful applications, for example, it causes unnecessary heating and wastage of power in electric motors, dynamos and in the cores of transformers
31. The working of speedometers of trains is based on:
a) wattles currents
b) eddy currents
c) alternating currents
d) pulsating currents
32. Identify the wrong statement:
a) Eddy currents are produced in a steady magnetic field
b) Induction furnace use eddy currents to produce heat.
c) Eddy currents can be used to produce breaking force in moving trains
d) Power meters works on the principle of eddy currents.
33. Which of the following is the best method to reduce eddy currents?
a) Laminating core
b) Using thick wires
c) By reducing hysteresis loss
d) None of these
34. The direction of eddy currents is given by:
a) Fleming’s left-hand rule
b) biot-savert law
c) Len’s law
d) Ampere circuital law
35. Eddy currents can be used to heat localised tissues of the human body, this branch of medical therapy is called
a) Hyperthermia
b) Diathermy
c) Inducthermy
d) None of These