UNIT 2 Components of a circuit In this unit you will learn about:
• conducting wires, which are usually made of metal • how switches control electrical circuits and cells, which are sources of energy.
Components of a circuit
There are a number of parts or components that an electrical circuit must have. Each component of the circuit has a symbol that we use to represent it in circuit diagrams. You learnt about these in Grade 6.
Conducting wires
Conducting wires are usually metal wires that carry the electric charges through the circuit. Conducting wires can be long or short.
Switches
• A switch can be inserted into a circuit to make a break in the circuit so that current does not flow.
• A switch is a convenient way in which to control the flow of electrical circuits. For example, we use switches to turn off the current in our homes.
Cells and batteries New words
cell – the smallest, whole, working part of a battery
potential energy – stored energy
battery – a collection of connected cells
• Cells are an energy source for electrical circuits. • Cells are chemical systems that store potential energy in the form of chemical substances. Potential energy is stored energy.
• When the circuit is completed, the chemicals in the cells react with one another to release energy. They release energy in the form of electrical energy, which produces an electric current.
• An electric current is the flow of charges through conducting wires. The charges have energy.
• When a number of cells are joined together, this is called a battery.
108 Topic 2 Energy transfer in electrical systems
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