Basic Electrical Engineering Questions and Answers – Reluctance

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

1. Reciprocal of reluctance is __________
a) Permeance
b) Susceptibility
c) Resistance
d) Conductance
View Answer

Answer: a
Explanation: The reciprocal of reactance is permeance. It is the ability of a material to allow the passage of magnetic lines of flux.

2. Reluctance is ________________ to the length of the material.
a) Directly proportional
b) Inversely proportional
c) Not related
d) Reluctance is ________________ to the length of the material.
View Answer

Answer: a
Explanation: The formula for reluctance is:
S = l/µ0 µr*A.
From the formula, we can see that reluctance is directly proportional to the length of the material.

3. Reluctance is ________________ to the area of cross section the material.
a) Directly proportional
b) Inversely proportional
c) Not related
d) Equal
View Answer

Answer: b
Explanation: The formula for reluctance is:
S = l/(µ0 µr*A).
From the formula, we can see that reluctance is inversely proportional to the area of cross section of the material.
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4. When the length of the material increases, what happens to reluctance?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero
View Answer

Answer: a
Explanation: Reluctance is directly proportional to the length of the material hence as length increases, reluctance also increases.

5. When the area of cross section of the material increases, what happens to reluctance?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero
View Answer

Answer: b
Explanation: Reluctance is inversely proportional to the area of cross section of the material hence as area increases, reluctance decreases.

6. Unit of reluctance is?
a) AWb
b) A2/Wb
c) Wb/A
d) A/Wb
View Answer

Answer: d
Explanation: Reluctance is magnetomotive force per unit flux,
So unit of reluctance = unit of MMF / unit of magnetic flux = A/Wb.

7. The electrical equivalent of reluctance is?
a) Resistance
b) Inductance
c) Capacitance
d) Conductance
View Answer

Answer: a
Explanation: Resistance is the opposition to the flow of charge, similarly reluctance is the opposition to the flow of magnetic flux.
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8. As the magnetic field strength increases, reluctance?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero
View Answer

Answer: a
Explanation: Reluctance is directly proportional to the strength of the magnetic field, hence as the strength of magnetic field increases, the reluctance increases.

9. As the magnetic flux density increases, the reluctance _____________
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero
View Answer

Answer: b
Explanation: Reluctance is inversely proportional to the magnetic flux density, hence as magnetic flux density increases, reluctance decreases.
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10. Calculate the reluctance when the magnetomotive force is 10A turns and the flux is 5Wb.
a) 0.5A/Wb
b) 5A/Wb
c) 10A/Wb
d) 2A/Wb
View Answer

Answer: d
Explanation: We know that:
F=ϕ*S
Substituting the given values from the question:
S=2A/Wb.

Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.

To practice all areas of Basic Electrical Engineering, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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