An ac source of period T and maximum voltage V is connected to a single unknown element. At time t = 0 the voltage is zero. At time t = T/4 the current in the unknown element is equal to zero, and at time t = T/2 the current is I = - I_max where I_max is the current amplitude. What is the unknown element? A)a resistor B)an inductor C)a capacitor D)an inductor or a capacitor E)More information is needed to identify the element.

Question

Quizplus · Accepted Answer

The current in a capacitor leads the voltage by 90 degrees. At t = T/4, the voltage is at its maximum, and the current is zero, which is consistent with a capacitor. At t = T/2, the voltage is zero, and the current is at its negative maximum, which also matches the behavior of a capacitor.

An Ac Source of Period T and Maximum Voltage V