Direct Current produces a magnetic field similar to a permanent magnet. This magnetic field:

Mr. Dubey • 52.30K Points
Coach Physics

Q. Direct Current produces a magnetic field similar to a permanent magnet. This magnetic field:

(A) is unidirectional and has a steady magnitude
(B) is unidirectional but its magnitude varies in regular pattern
(C) has steady magnitude but changes direction in regular pattern
(D) changes direction and magnitude in regular pattern

Correct Answer - Option(A)

Explanation by: Mr. Dubey

A coil or conductor carrying direct current (DC) produces a magnetic field similar to a permanent magnet. The current carried by this conductor is unidirectional and steady i.e. it does not change direction or vary in magnitude with respect to time. Hence, the effect is that of a permanent magnet which simply attracts objects near the coil. However, in case of Alternating current, the magnetic field changes direction, i.e. it becomes negative for the second half of the frequency cycle (50 cycles per second in India). Further, its magnitude varies sinusoidally (curve having a sinewave form) thereby becoming zero at the end of a cycle.

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