A winding (conductor) carrying direct current (DC) produces a magnetic field akin 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. The case is different with alternating current (AC) which changes direction, i.e. it becomes negative for the second half of the frequency cycle (which is 50 cycles per second in India). Also, the magnitude varies sinusoidally (curve having a sine wave form) thereby becoming zero at the end of a cycle. Alternating current produces an alternating magnetic field which induces an alternating current in the object placed near it. This induced current or voltage always opposes the magnetic field inducing it, and hence the object is repelled.
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