The Current in an Alternating Circuit Varies in Intensity with Time

Multiple Choice

The current in an alternating circuit varies in intensity with time. If I represents the intensity of the current and t represents time, then the relationship between I and t is given by I = 20cos 160 πt where I is measured in amperes and t is measured in seconds. Find the maximum value of I and the time it takes for I to go through one complete cycle. ​

A) The maximum value of I is 40 amperes; one complete cycle takes  seconds.
B) The maximum value of I is 5 amperes; one complete cycle takes  seconds.
C) The maximum value of I is 20 amperes; one complete cycle takes  seconds.
D) The maximum value of I is 40 amperes; one complete cycle takes  seconds.
E) The maximum value of I is 20 amperes; one complete cycle takes  seconds.