Monday, 3 December 2012


1. Electricity is used at home and at work for lighting and to power machines.
2. Electric lamps, computers, television sets and many other electric appliances and machines use elelctricity.
3. The following are various sources of electricity.

Electricity from chemical reactions

The following electrical sources generate electricity through chemical reactions.

Dry cells
  • Easy to be carried anywhere but cannot be recharged.
  • Used in alarm clocks, torches, radios, toys and cameras.
  •  Supply greater amounts of electricity. Heavy and inconvenient to use.
  • Used in motor vehicles to start the engines and to light up lamps.
  • Can be recharged.
Rechargeable batteries
  • Small, can be carried around easily. Can be recharged.

  • Used in computers, laptops, toys and mobile phones.
Electric generators (dynamos)

1.It is the most important source of electricity in our homes. Electricity is generated by turning the electric generators.

(a) The generators in a hydroelectric power station are turned by flowing water from dams.
(b) They can also be turned by steam engines, wind and wave actions.

  • Transforms the kinetic energy of water into electrical energy.

2. Bicycle dynamos are also electric generators.
  •  A rotating magnet inside a coil of wire transforms kinetic energy into electrical energy.
3. Electricity that is generated by electric generators are carried to home and factories through cables.

4. Most household electric appliances work when they are plugged into power points and switched on.

Solar cells and solar panels

  • Used in calculators, wristwatches, houses and satellites.
  • Converts light energy from the Sun into electrical energy.

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