Why is the answer for this question (B) and not (A).

Solution:

Direct current always flows in one direction but the alternating current reverses its direction periodically.
Frequency of the AC is given 60 Hz, which means it completes 60 cycles in one second. And in each cycle it alters the direction twice.
​​​​Therefore AC changes direction 2×60=120 times in one second.


Hence, the correct answer is option (B).
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