Electrical Engineering - Magnetism and Electromagnetism

Exercise :: Magnetism and Electromagnetism - General Questions

21. 

An electromagnetic field exists only when there is

A. an increasing current
B. decreasing current
C. voltage
D. current

Answer: Option D

Explanation:

No answer description available for this question. Let us discuss.

22. 

When a solenoid is activated, the force that moves the plunger is

A. an electromagnetic field
B. a permanent magnetic field
C. varying voltage
D. a steady current

Answer: Option A

Explanation:

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23. 

What is the magnetomotive force (mmf) of a wire with 8 turns carrying three amperes of current?

A. 2,400 At
B. 240 At
C. 24 At
D. 2.4 At

Answer: Option C

Explanation:

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24. 

If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage

A. remains unchanged
B. reverses polarity
C. increases
D. decreases

Answer: Option C

Explanation:

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