Home » Alternating Current » 4 » b The current in an AC circuit completes a cycle in 0.1 second. So the frequency is:   a.   1 Hz   b.   10 Hz   c.   100 Hz   d.   1000 Hz Your answer "b" is CORRECT! The frequency is the reciprocal of the period. 1 / 0.1 = 10 Hz. Next