# Basic Electrical Engineering Questions and Answers – Mutual Inductance

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This set of Basic Electrical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Mutual Inductance”.

1. The phenomenon due to which there is an induced current in one coil due to the current in a neighbouring coil is?
a) Electromagnetism
b) Susceptance
c) Mutual inductance

Explanation: When there is a current in a coil, due to the magnetic field caused by the current there is current induced in the neighbouring coil as well. This is known as mutual inductance.

2. If the current in one coil becomes steady, the current in neighbouring coil is?
a) Zero
b) Infinity
c) Doubles
d) Halves

Explanation: A current is induced when there is changing magnetic flux. Hence the induced current in neighbouring coil is zero when the current is steady.

3. If the current in one coil is steady, what happens to the mutual inductance?
a) Zero
b) Infinity
c) Doubles
d) Halves

Explanation: A current is induced when there is changing magnetic flux. The induced current in neighbouring coil is zero when the current is steady. So, mutual inductance is zero.

4. What is the SI unit of mutual inductance?
a) Ohm
b) Henry
c) Volt
d) Siemens

Explanation: Mutual inductance is the inductance between the two neighbouring coils. Since it is a type of inductance, its unit is that of inductance, that is, henry.

5. Which, among the following, is the correct expression for mutual inductance?
a) M=N2φ2/I2
b) M=N2φ2/I1
c) M=N1φ2/I2
d) M=N1φ1/I1

Explanation: Mutual inductance is the product of the number of turns in one coil and the flux linkages of that coil, divided by the current in the other coil. Hence M=N2φ2/I1 is the correct expression.

6. If the flux linkage in coil 1 is 3Wb and it has 500 turns and the current in coil 2 is 2A, calculate the mutual inductance.
a) 750H
b) 500H
c) 450H
d) 900H

Explanation: We know that mutual inductance is the product of the number of turns in one coil and the flux linkages of that coil, divided by the current in the other coil.
M=3*500/2=750H.

7. The flux linkage in coil 1 is 3Wb and it has x turns and the current in coil 2 is 2A, calculate the value of x if the mutual inductance is 750H.
a) 300
b) 400
c) 500
d) 700

Explanation: We know that mutual inductance is the product of the number of turns in one coil and the flux linkages of that coil, divided by the current in the other coil.
N=750*2/3 = 500 turns.

8. The flux linkage in coil 1 is x and it has 500 turns and the current in coil 2 is 2A, calculate the value of x if the mutual inductance is 750H.
a) 1Wb
b) 2Wb
c) 3Wb
d) 4Wb

Explanation: We know that mutual inductance is the product of the number of turns in one coil and the flux linkages of that coil, divided by the current in the other coil.
φ=750*2/500 = 3Wb.

9. The flux linkage in coil 1 is 3 Wb and it has 500 turns and the current in coil 2 is xA, calculate the value of x if the mutual inductance is 750H.
a) 1A
b) 2A
c) 3A
d) 4A

Explanation: We know that mutual inductance is the product of the number of turns in one coil and the flux linkages of that coil, divided by the current in the other coil.
I=3*500/750 = 2A.

10. Practical application of mutual inductance is ____________
a) DC generator
b) AC generator
c) Transformer
d) Capacitor

Explanation: A transformer is a device made of two or more inductors, one of which is powered by AC, inducing an AC voltage across the second inductor.

11. The types of inductors are ____________
a) Fixed and variable
b) Only fixed
c) Only variable
d) Neither fixed nor variable

Explanation: The two types of inductors are fixed and variable inductors. Fixed inductors are those whose inductance value cannot be changed. Variable inductors are those whose values can be changed as and when required.

Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.

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