Class 12 Physics Chapter 4 Moving Charges And Magnetism MCQs

1 Tesla is a unit of:

A electric flux

B magnetic flux

C magnetic field

D electric field

View Answer

Answer:magnetic field

2 A cyclotron can be used to produce high energy:

A neutrons

B deutrons

C β particles

D α partifcles

View Answer

Answer:α partifcles

3 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:

Class

A √2 p

B p/√2

C P

D 2p

View Answer

Answer:√2 p

4 An electron having mass ‘m’ and Kinetic energy E enters in uniform magnetic field B perpendicular, then its frequency will be:

A eE/qmB

B 2πm/eB

C eB/2πm

D 2m/eBE

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Answer:eB/2πm

5 The torque acting on a magnetic dipole of moment

when placed in a magnetic field

A p_mB

B

C

D

View Answer

Answer:

6 A charge q moves in a region, where electric field E and magnetic field B both exist, then force on it is :

A

B

C

D

View Answer

Answer:

7 A charged particle of mass m and charge q travels on a circular path of radius r i.e., perpendicular to the magnetic field B. The time taken by particle to complete on revolution is :

A 2πqB/m

B 2πm/qB

C 2πmq/B

D 2πq²B/m

View Answer

Answer:2πm/qB

8 The permeability of a paramagnetic substance is:

A very large

B small but more than unity

C less than unity

D negative

View Answer

Answer:small but more than unity

9 A current carring coil is placed in a uniform magnetic field. If the coil turns through an angle θ, then the torque is directly proportional to:

A sin θ

B cos θ

C cot θ

D tan θ

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Answer:cos θ

10 The current sensitibility of a moving coil galanometer increases with decrease in:

A magnetic field

B area of a coil

C number of turns

D None of these

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Answer:None of these

11 In thomson spectrograph

then velocity of electron beam will be:

A

B

C

D E² / B²

View Answer

Answer:

12 The force

experienced by a particle of charge q moving with velocity

in a magnetic field

is given by,

A

B

C

D

View Answer

Answer:

13 According to Ampere’s Circuital law

A

B

C

D

View Answer

Answer:B

14 A positive charge enters in a magnetic field and travels parallel to but opposite the field. If experiences

A an upward force.

B a downward force.

C an accelerated force.

D no force.

View Answer

Answer:an accelerated force.

15 An electron is projected along the axis of a circular conductor carrying the same current. Electron will experience

A a force along the axis.

B a force perpendicular to the axis.

C a force at an angle of 4° with axis.

D no force experienced.

View Answer

Answer:no force experienced.

16 The gyro-magnetic ratio of an electron in an H-atom, according to Bohr model, is

A independent of which orbit it is in.

B neutral

C positive

D increases with the quantum number n.

View Answer

Answer:independent of which orbit it is in.

17 A conducting circular loop of radius r carries a constant current i. It is placed in a uniform magnetic field B, such that B is perpendicular to the plane of the loop. The magnetic force acting on the loop is

A irB.

B 2πriB

C zero

D πriB

View Answer

Answer:zero

18 If the beams of electrons and protons move parallel to each other in the same direction, then they

A attract each other.

B repel each other.

C no relation.

D neither attract nor repel.

View Answer

Answer:repel each other.

19 A current loop placed in a non-uniform magnetic field experiences

A a force of repulsion.

B a force of attraction.

C a torque but not force.

D a force and a torque.

View Answer

Answer:a force and a torque.

20 The maximum current that can be measured by a galvanometer of resistance 40 Ω is 10 mA. It is converted into voltmeter that can read upto 50 V. The resistance to be connected in the series with the galvanometer is

A 2010 Ω

B 4050 Ω

C 5040 Ω

D 4960 Ω

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