Electromagnetism MCQs

Question 1

At one instant an electron is moving in the positive x direction in a region where there is a uniform magnetic field in the positive z direction. When viewed from a point on the positive z axis, its subsequent motion is:

Accepted Answer

Clockwise around a circle in the xy plane

Answer

Straight ahead

Answer

Counterclockwise around a circle in the xy plane

Answer

In the positive z direction

Question 2

When a charged particle enters a magnetic field at an angle of 45° , its path in the magnetic field will be:

Accepted Answer

Helical

Answer

Circular

Answer

Parabolic

Answer

Hyperbolic

Question 3

Force acting on a moving charge in a magnetic field will not depend on:

Accepted Answer

Its mass

Answer

Amount of charge

Answer

Its velocity

Answer

Intensity of magnetic field

Question 4

An "α" particle enters a magnetic field of strength "B" with a speed "v" parallel to the direction of the magnetic field. The force on the particle is:

Accepted Answer

Zero

Answer

Bev

Answer

Bev/2

Answer

Infinite

Question 5

The magnetic field produced due to the current in a straight wire is proportional to the:

Accepted Answer

Electric current

Answer

Length of the wire

Answer

Conducting material

Answer

Diameter of the wire

Question 6

The magnetic field due to the electric current in a conducting straight wire is:

Accepted Answer

Circular around the conducting wire

Answer

Towards the centre of the conducting wire

Answer

In the direction of the electric current

Answer

In the direction opposite to the electric current

Question 7

A uniform electric field and a uniform magnetic field exist in a region in the same direction. An electron is projected with a velocity pointed in the same direction. The electron will:

Accepted Answer

Keep moving in the same direction but its speed will decrease

Answer

Turn to its right

Answer

Turn to its left

Answer

Keep moving in the same direction but its speed will increase

Question 8

Which of the following does not affect the motion of a moving electron?

Accepted Answer

Magnetic field applied in the direction of motion

Answer

Electric field applied in the direction of motion

Answer

Electric field applied perpendicular to the direction of motion

Answer

Magnetic field applied perpendicular to the direction of motion

Question 9

A current of 2A is passing through an inductor of 2mH. Energy stored by it is:

Accepted Answer

4 mJ

Answer

8 mJ

Answer

10 mJ

Answer

6 mJ

Question 10

The radius of curvature of the path of a charged particle moving in a static uniform magnetic field is:

Accepted Answer

Directly proportional to the magnitude of the linear momentum of the particle

Answer

Directly proportional to the magnitude of the charge on the particle

Answer

Directly proportional to the kinetic energy of the particle

Answer

Inversely proportional to the magnitude of the magnetic field

Question 11

Coils P and Q each have a large number of turns of insulated wire. When switch S is closed, the pointer of galvanometer G is deflected toward the left. With S now closed, to make the pointer of G deflect toward the right one could:

Accepted Answer

Open S

Answer

Move coil P toward coil Q

Answer

Move coil Q toward coil P

Answer

Move the slide of the rheostat R quickly to the right

Question 12

A charged particle (q = +2 μC, m = 2 × 10⁻⁶ kg) moves at 5 × 10⁴ m/s perpendicular to a magnetic field of 0.4 T. The radius of its circular path is:

Accepted Answer

0.025 m

Answer

0.0125 m

Answer

0.05 m

Answer

0.1 m

Question 13

A rectangular coil of 50 turns, area 0.02 m², rotates at 10 Hz in a uniform magnetic field of 0.5 T. The maximum induced emf is:

Accepted Answer

31.4 V

Answer

15.7 V

Answer

62.8 V

Answer

78.5 V

Question 14

A straight wire of length 0.2 m carries a current of 5 A in a uniform magnetic field of 0.3 T at 30° to the field. The force on the wire is:

Accepted Answer

0.15 N

Answer

0.3 N

Answer

0.5 N

Answer

0.75 N

Question 15

A solenoid of 200 turns, length 0.5 m, and radius 0.02 m carries a current of 2 A. The magnetic field at its center is (μ₀ = 4π × 10⁻⁷ T·m/A):

Accepted Answer

4 × 10⁻³ T

Answer

2 × 10⁻³ T

Answer

8 × 10⁻³ T

Answer

1.6 × 10⁻² T

Question 16

A circular loop of radius 0.1 m with 100 turns is in a magnetic field of 0.2 T. If the field decreases to 0.1 T in 0.01 s, the induced emf is:

Accepted Answer

31.4 V

Answer

62.8 V

Answer

15.7 V

Answer

7.85 V

Question 17

A proton (q = 1.6 × 10⁻¹⁹ C, m = 1.67 × 10⁻²⁷ kg) moves at 2 × 10⁶ m/s perpendicular to a 0.5 T magnetic field. The frequency of its circular motion is:

Accepted Answer

7.64 × 10⁶ Hz

Answer

3.82 × 10⁶ Hz

Answer

1.91 × 10⁶ Hz

Answer

15.28 × 10⁶ Hz

Question 18

A bar magnet is moved toward a coil of 50 turns at 0.5 m/s, changing the magnetic flux at a rate of 0.02 Wb/s. According to Lenz's law, the direction of the induced current in the coil is such that it:

Accepted Answer

Repels the magnet

Answer

Attracts the magnet

Answer

Does not affect the magnet

Answer

Rotates the magnet

Question 19

A rectangular coil of dimensions 0.1 m × 0.2 m with 20 turns rotates at 1200 rpm in a 0.6 T magnetic field. The peak emf induced is:

Accepted Answer

60.3 V

Answer

30.2 V

Answer

75.4 V

Answer

90.5 V

Question 20

Two parallel wires 0.1 m apart carry currents of 10 A each in opposite directions. The force per unit length on one wire is (μ₀ = 4π × 10⁻⁷ T·m/A):

Accepted Answer

2 × 10⁻⁴ N/m

Answer

4 × 10⁻⁴ N/m

Answer

1 × 10⁻⁴ N/m

Answer

8 × 10⁻⁴ N/m

Free Electromagnetism MCQs with Answers