# Magnetism and Electromagnetism MCQ Questions & Answers

Magnetism and Electromagnetism MCQs : This section focuses on the "Magnetism and Electromagnetism". These Multiple Choice Questions (MCQs) should be practiced to improve the Magnetism and Electromagnetism skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

What is the reluctance of a material that has a length of 0.045 m, a cross-sectional area of 0.015 m2, and a permeability of 2500 µWb/At·m?

A. 833.33 µAt/Wb
B. 0.27 At/Wb
C. 1200 At/Wb

Question 2

A Hall effect sensor

A. exists only in theory
B. is a noncontacting magnetic sensor
C. can operate only a few times before failure
D. produces very large voltages

Question 3

What is the magnetomotive force in a 150-turn coil of wire with 2 A flowing through it?

A. 13.33 mAt
B. 300 At
C. 75 At
D. 152 At

Question 4

Permeability is the inverse equivalent of which electrical term?

A. Voltage
B. Current
C. Resistance
D. Conductance

Question 5

Which electromagnetic device has a movable iron core called a plunger?

A. A speaker
B. A dc generator
C. A relay
D. A solenoid

Question 6

The polarity of induced voltage while a field is collapsing is

A. independent of the force creating the field
B. opposite to the force creating the field
C. identical to the force creating the field
D. present only if the force is stationary

Question 7

"Series" and "parallel" as applied to dc motors refer to

A. the connection of the motor and controller
B. the connection of the field coil and armature windings
C. the connection of the brush and commutator
D. the connection of the motor batteries

Question 8

What is the flux density of a magnetic field whose flux is 3000 µWb and cross-sectional area is 0.25 m2?

A. 12,000 T
B. 83,330 T
C. 0 T

Question 9

The Hall effect

A. is a phenomenon with no practical applications
B. is used in various sensor applications
C. can develop potentials of thousands of volts
D. is the basis for solar cell operation

Question 10

Which electromagnetic device contains an armature?

A. A speaker
B. A dc generator
C. A relay
D. A solenoid

Question 11

The component that produces power in an electromagnetic generator is called the

A. armature
B. field winding
C. commutator
D. brush

Question 12

Which electromagnetic device has a flexible cone?

A. A speaker
B. A dc generator
C. A relay
D. A solenoid

Question 13

What do you call the characteristic of a magnetic material whereby a change in magnetization lags the application of a magnetizing force?

A. Hysteresis
B. Induction
C. Retentivity
D. Reluctance

Question 14

The unit of flux density is known as

A. magnetomotive force
B. a weber
C. a maxwell
D. a tesla

Question 15

What are the effects of moving a closed wire loop through a magnetic field?

A. A voltage is induced in the wire.
B. A current is induced in the wire.
C. The polarity across the wire depends on the direction of motion.
D. All of the above