- Energy is the ability to do work.
- When you are able to push or pull an object through a distance in the direction of the push or pull then you have done some work.
- Energy is what one uses to do work.
- Energy is what a bulb, for example, uses to light up, or what a magnet uses to attract a nail.
- We need energy to do a lot of things for example for lighting, cooking, ironing, and listening to the radio.
- Energy is classified according to its source or according to the work it does.
- The various types of energy include:
1. Chemical energy
2. Heat energy
3. Light energy
4. Magnetic energy
5. Electrical energy
6. Sound energy
This is the stored energy that can be released when it is broken down.
For example, when charcoal is burnt it produces heat.
This is because charcoal has chemical energy stored in it.
Chemical energy is stored in dry cells, food and fuels.
This is the energy that causes a change in temperature.
Everything has some heat energy.
The hotter something is, the more heat energy it has.
Heat energy is transferred from hot regions to cold regions because of the temperature difference between them.
Heat energy may be useful in cooking food, ironing and drying clothes among others.
Anything that glows gives out light energy.
Things like the sun, light bulbs, candles and glow worms give out light.
Light is the form of energy that enables us to see.
Burning objects also produce light energy.
Magnets are metals that attract other metals.
Metals that are attracted by magnets are said to be magnetic.
Examples of magnetic materials are iron, nickel, cobalt and steel.
The ability of magnets to pull or push things is called magnetism.
Electrical energy is produced by electricity.
It is produced when a circuit is complete, the switch is on and current is flowing through the circuit.
Some sources of electrical energy include generators, batteries and cells.
Lightning is also a form of electric energy.
Electrical energy is a very useful form of energy because it is easily converted into other forms of energy.
Sound is a form of energy that is produced by vibrating objects.
For example, our voices, radios and musical instruments produce sound as a result of vibration.
Sound can also be produced by hitting a drum, plucking strings like in a guitar and blowing flutes and whistles.