Chapter 37, Problem 35A

An electric hair drier running at normal speed draws a relatively small current. But if somehow the motor shaft is prevented from turning, the current dramatically increases and the motor overheats. Why?

To determine

To explain: the reason for the overheating of electric hair drier motor when the motor shaft does not rotate.

Answer to Problem 35A

The motor overheats due to more heat energy developed in the drier.

Explanation of Solution

Introduction:

As per the law of conservation of energy, there is no energy creation and demolition. It is converted from one form to other.

As the motor rotates the electrical energy is converted into mechanical energy. There will be some heat energy is also present due to the heating effect of the current. but when the motor of the hair drier stops all electrical energy converted into heat energy and a large amount of current is passed through the coils of the motor and the motor gets overheats.

Conclusion:

The overheating of the motor as the more heat energy is developed as all the electrical energy is converted into heat energy when the motor does not rotate.