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Making Electricity
General
You probably use several things every day which need batteries e.g. radio, MP3 player,
calculator, watch. There are several different kinds of battery, but they all do the
same thing – they provide us with a convenient and portable source of electricity. This
topic allows us to study how electricity is made from the chemicals in a battery.
Chemical reactions, as you know, often result in changes in appearance or temperature.
Chemical reactions also take place when batteries produce electricity.
Apparatus which produces electricity from chemical reactions is usually called a cell.
A battery is really two or more cells joined together.
Cells
General
The lead-acid ‘battery’ is an example of a wet cell. These are not very suitable for
many purposes.
The batteries we use in most everyday appliances are dry cells, where the liquid or
solution of the wet cell is replaced by a thick paste. This paste is often in the form of
ammonium chloride.
All batteries change chemical energy into electrical energy (electricity). This
electricity can pass along metal wires as a flow of electrons.
All cells, whether wet or dry, become run down. This usually requires the batteries
having to be replaced as the chemicals which produced the electricity have been used
up.
Some kinds of cell can be recharged and used again. These cells are called
rechargeable cells. The lead-acid cell is an example of a rechargeable cell.
When a cell is charged, electrical energy is changed into chemical energy in the cell
because of the chemical reactions which take place.
When the cell is discharged, different chemical reactions take place, and the
chemical energy stored in the cell is changed into electrical energy.