Turn Off The Light

Electricity in The home 

Electricity in The home

Modern houses contain parallel circuits called ring mains. One circuit is for the lighting, the other is the main circuit. Access to the main circuit is made possible through wall sockets. All household lights and appliances are connected in parallel, as this allows all devices to operate on the same voltage (level of power). This voltage will not change if a piece of equipment is added or taken away (see page 22). The current leaves the house through another wire. Faulty wiring may cause a fire in the home. To avoid such a risk, plugs and circuits are fitted with fuses. A fuse is a piece of wire designed to melt, and so break a circuit, if the current is too high. A complex circuit, like that in a television set has hundreds or even thousands of circuit parts. They consist of both parallel and series circuits. Make your own game using circuits and switches.

 Turn Off The Light

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1. You will need a large board, three bulbs, three batteries, lengths of insulated wire, drawing pins, plasticine and paper clips.
 

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2. Place a battery in three corners of the board. Make sure that unlike terminals are facing. Attach the wires using plasticine
 

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3. Connect the bulbs to the batteries as shown. Leave gaps in the circuits for switches. These can be paperclips and drawing pins.
 

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4. Connect each switch by pressing down a paper clip on to a drawing pin. Observe the brightness of the bulbs. If any of the bulbs do not work, check all connections.
 

Turn Off The Light

5. Now experiment with your circuit board. Can you light up only one bulb at a time by disconnecting certain switches? Now try lighting up two bulbs simultaneously. You can have hours of fun trying various connections. Observe the bulbs. When do they glow most brightly? When are they dimmest?

 

Why It Works

The flow of electrons is regulated by connecting and disconnecting the switches on the circuit board. When a bulb is isolated by disconnecting a switch, the circuit into which it is wired is broken. When every switch is connected, all the bulbs glow. The high resistance of a fuse restricts the amount of current that can pass through. Each appliance needs a fuse of the correct resistance (see page 20).

 

Bright Ideas

• Position the batteries so that like terminals are facing each other. What effect does this have on your circuit board? Can the bulbs be lit up simultaneously now? Why is this? Remember that electrons travel from negative to positive. Do the bulbs glow just as brightly as before?
• If you remove one bulb, how does this affect the circuits?
• Ask an adult to show you where the electricity meter is located in your house. Keep a record of meter readings in your home for a week. Work out how much electricity has been used. Use your figures to make a graph. You could put the information on to a computer database if you have one at home or school. Count the number of sockets in your home. Make a list of all the electrical appliances used by your family. Watch the meter dials when each appliance is being used - which uses the most electricity? Work out some ways in which your family could save electricity.