Chapter 21, Problem 1RQ

In a pure capacitive circuit, does the current lead or lag the voltage?

To determine

Whether the current leads or lags the voltage in a pure capacitive circuit.

Answer to Problem 1RQ

In a pure capacitive circuit, the current leads the applied voltage by .

Explanation of Solution

Description:

As can be seen from the above figure,

• At 0°, value for the applied voltage is zero, while the graph for current is at its positive peak.

• At 90°, value for the applied voltage is at its positive peak , while the graph for current is at zero.

• At 180°, value for the applied voltage is zero, while the graph for current reaches negative peak.

• At 270°, value for the applied voltage reaches negative peak, while the graph for current rises towards zero from the negative peak.

From the above pattern it can be interpreted that current leads the applied voltage by in pure capacitive circuit.