Chapter 25.1, Problem 15SSC

To determine

Whether the power of an AC source dissipates when the current is negative.

Explanation of Solution

Introduction:

The rate at which energy is consumed is called power. It is the product of current and voltage.

In an AC supply, there is no dissipation of power when the current is negative, as when current is negative, so is voltage. Power is the product of current and voltage therefore, power is positive. When current is positive, voltage is positive and so is power. Hence, complete energy is transferred to the lamp.

Conclusion:

When current is negative, voltage is negative, hence power is positive.