Chapter 22.2, Problem 36SSC

To determine

In which setting, it would be smaller resistance in a hair dryer.

Explanation of Solution

Introduction:

The hair dryer works at a fixed voltage supply. The different settings, hot and warm, correspond to different power usage.

Power is $P=IV$ . For a fixed voltage the power is varied by drawing different amounts of current. For more power more current is required for less power less current.

Current in a circuit is given by $I=\frac{\text{V}}{R}$ . Hence for a fixed voltage higher current is drawn by low resistance setting.

The hot mode in the hair dryer uses more power, which requires larger current hence in this setting the resistance is lower.

Conclusion:

The hot mode in the hair dryer uses more power, which requires larger current hence in this setting, the resistance is lower.