Changing form

The idea

Energy exists in many forms, such as mechanical, electrical, light, thermal, chemical and sound energy, and can be changed from one form to another.

A bulb and a heater

A bulb glows when you switch it on. A water heater warms the water. A ringing bell makes a sound.

What do you think the bulb, the heater and the bell have in common?

• Each changes energy from one form to another
• Each creates new energy from nothing
• Each stores energy and gives none out

Match the change

Tap a thing on the left, then the change that happens in it.

Many forms

Each of these changed energy from one form into another. Energy exists in forms such as mechanical, electrical, light, thermal, chemical and sound energy, and it can be changed from one form to another.

Energy exists in many forms, such as mechanical, electrical, light, thermal, chemical and sound energy, and it can be changed from one form to another.

Notes

Energy exists in many forms (mechanical, electrical, light, thermal, chemical, sound) and can be changed from one form to another.

Check yourself

In an electric bulb, electrical energy is converted into…

In an electric water heater, electrical energy is converted into…

The food we eat powers our muscles. What conversion takes place?

A ringing bell converts…

• chemical energy. Chemical energy is the energy in food, for example. In a bulb, electrical energy becomes light.
• light energy — correct. Yes!
• sound energy. A ringing bell gives sound energy. In a bulb, electrical energy becomes light.
• mechanical energy of the water. The water is warmed, so its thermal energy increases. The heater does not move it as mechanical energy.
• sound energy. The heater warms the water. The conversion to sound energy happens in a ringing bell.
• thermal energy of the water — correct. Yes!
• Chemical energy to mechanical energy — correct. Yes!
• Light energy to chemical energy. The food has chemical energy, which the muscles use. The change is not from light energy.
• Sound energy to thermal energy. The chemical energy in food is converted into the mechanical energy of the muscles.
• sound energy into mechanical energy. The book says a ringing bell converts mechanical energy into sound energy, so the change goes the other way.
• mechanical energy into sound energy — correct. Yes!
• light energy into sound energy. A ringing bell converts mechanical energy into sound energy, not light energy into sound energy.