physics MCQs – Page 20

Practise multiple-choice questions from physics for competitive examinations and subject revision. Review each marked answer and report any item that may be outdated or unclear.

physics Mcqs

381. An alternating current of the r.m.s value of 4.0 A and frequency 50Hz flows in a circuit containing a 10? resistor. The peak current is then ?
0

A. 20A

B. 20.66A

C. 6.66A

D. 5.66A

382. The standard vector symbol for flux density is ____________________?
0

A. B

B. H

C. M

D. L

383. Which one of the following material is most suitable for making core of an electromagnet ?
0

A. air

B. soft iron

C. steel

D. Cu-Ni alloy

384. What is the value of the current in a wire of 10cm long at the right angle to a uniform magnetic field of 0.5 Weber/m2 when the force acting on the wire is 5N ?
0

A. 1A

B. 1000A

C. 10A

D. 100A

385. Alpha particle ionizes an atom_________________?
0

A. Through electrostatic attraction

B. Through electrostatic repulsion

C. Through direct collision

D. All of above

386. Magnetic flux and flux density are related by___________________?
0

A. magnetic flux = flux density / area

B. flux density = magnetic flux x area

C. flux density = magnetic flux area

D. magnetic flux = flux density x area

387. An electron enters a region where the electric field E is perpendicular to the magnetic field B. It will suffer no deflection if_________________?
0

A. E = BeV

B. E = BV

C. B = eE/V

D. E = BeV/2

388. The unit of radioactivity curie is equal to_________________?
0

A. 3.60 x 1010 disintegration per sec

B. 3.70 x 1010 disintegration per sec

C. 3.74 x 109 disintegration per sec

D. 3.55 x 1010 disintegration per sec

389. While measuring the unknown resistance the help of slide wire bridge a greatest accuracy can be achieved when__________________?
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A. a most sensitive galvanometer is used

B. a steady voltage cell is used

C. a high resistance box is used in one of its gap

D. the balance point is close to the middle of the wire

390. Work done will be maximum if the angle between the force F and displacement d is______________________?
0

A. 180

B. 90

C. 45

D. 0

391. During fusion of hydrogen into helium________________?
0

A. Energy is absorbed

B. Mass is increased due to energy absorption

C. Energy is released

D. Mass is reduced due to the energy released

392. The dimension of torque is______________?
0

A. [ML2T-2]

B. [ML-2T-2]

C. [MLT-2]

D. [ML2T]

393. In simple cube one atom or molecule lies at its______________________?
0

A. Force corners

B. Nine corners

C. Eight corners

D. Six corners

394. Coercive force is the force which opposes ____________________?
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A. Demagnetization

B. Surface cracking

C. Breakage

D. Extension

395. Work done by the force of friction is____________________?
0

A. positive only for small frictional force

B. always positive

C. positive only for large frictional force

D. always negative

396. The energy liberated when one atom of U-235 undergoes fission reaction is________________?
0

A. 200MeV

B. 40MeV

C. 20MeV

D. 30MeV

397. Two vectors are A = 3i^+2j^ -k^& B = 3i^-2j^ +k^ , then_____________?
0

A. B is anti-parallel to A

B. B is a negative vector of A

C. B is perpendicular to A

D. B has a negative magnitude

398. Diffraction fringes are____________________?
0

A. distance between then decreases

B. they are adjacent with no space in between

C. equally spaced

D. distance between them increases

399. Three coplanar forces acting on a body keep it in equilibrium. They should therefore be_______________?
0

A. Parallel

B. Concurrent

C. Non-parallel

D. Non-concurrent

400. The energy band occupied by the valence electrons is called___________________?
0

A. conduction band

B. Energy state

C. Valence band

D. ve energy state

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