A game of nerves!

A simple circuit

A simple circuit

Due to the scientific experiments with electricity and magnetism carried out by men like William Faraday, it is now possible to make large amounts of electricity. It can be carried along wires to our homes like water in a pipe, from a power station. Then it is turned into light, heat and mechanical energy. Every time you switch on a light you are completing a pathway for the electricity, called a circuit. This allows the current to flow through electrical appliances. It was not until the 1950s that most homes were finally wired up to receive electricity and there are still some areas of the world that have no electricity at all. Our homes are supplied from mains electricity (see page 24). Do not try to use mains electricity for the projects in this book - it is dangerous. Using a battery, you can set up a game which needs only a simple, safe electric circuit.

A game of nerves!

A game of nerves 01

1. You will need a small 6 volt bulb in a bulb holder. You can buy one of these from an electrical shop. Attach two lengths of insulated wire on either side.

A game of nerves 02

2. Form a loop with a piece of thin wire, as shown, and connect it to a long length of insulated wire. Put a plastic straw around the join to form a handle.

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3. Now ask an adult to open up a wire coat hanger and bend it into bumps and curves. Attach one side of the bulb holder to the bare wire, taking the other end to two batteries.

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4. Attach the wire loop to the other end of the batteries. You can use plasticine to hold the wires on the battery terminals.

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 5. Hide the batteries inside a piece of polystyrene and stand the bent wire on the top. Pass the loop along the wire. If the bulb lights up, try again.

 

Bright ideas

Bright ideas
Make the game more difficult by making the wire loop smaller. Extend the length of the circuit by using a longer piece of wire. Now you can put in more curves or bends.
Demonstrate how a short circuit can happen by setting up a simple closed circuit using bare wire. Lay a metal conductor, such as a screwdriver, across both wires - the bulb will go out.
Try adding another battery - what do you notice? How long does the bulb last?

Why it works
The flow of electrons around a complete circuit is called a current. The current must have somewhere to flow to. Electrons flow from the negative terminal on a battery to a positive terminal. In this game the circuit is only completed when the bare wire of the loop makes contact with the bare wire that connects the bulb with the battery.

A game of nerves