We can tell if a current is flowing through a circuit by checking whether a bulb lights up. This is shown in the photograph of a circuit below.


Figure 2 The circuit is complete so the bulb lights up. Did you know?


An incandescent bulb is a type of electric light bulb commonly found in people’s homes. It has a filament that is heated by an electric current until the heat energy changes to light energy and the bulb lights up.


Figure 3 These devices change electrical energy into other types of energy. heat


sound


movement


You will learn about output devices in Topic 3 Unit 2.


Unit 1 Circuits and current electricity 107


STRAND 3


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