Chapter 24, Problem 43A

In buildings that are being heated electrically, is it wasteful to turn on all the lights? Is turning on all the lights wasteful if the building is being cooled by air conditioning? Defend your answers.

To determine

To Explain: Whether the turning on the lights for heating up is wasteful or not when the building is heated up electrically and when cooled using the air conditioner.

Explanation of Solution

Introduction:

In electric bulbs, the electric energy is converted into the light as well as heat energy. The light is produced when filament gets heated up as current passes through it.

Energy is always wasted when lights are turned on. This is because most of the energy is dissipated as heat while the only a small amount is converted into light. A lightbulb is especially very inefficient source of light.

For the purpose of heating up, the lights would not be wasteful in case the building is being heated electrically. Turning on lights in order to heat up the room would be actually useful because majority of the electrical energy is dissipated as heat.

It would be wasteful to turn on the lights while the air conditioner is used because the air conditioner would have to do more work to further cool the room.