Using conductors and insulators in electrical appliances
This Topic is About...
- I will classify materials used in electrical appliances as conductors or insulators.
- I will see how to use electrical appliances safely.
- I will predict whether appliances are being used safely or not.
- I will present results in a dot plot.
You’re going to be a science explorer!
Key Words
- cable
- cord
- electric shock
- mains electricity
- plug
- pylon
- volt
- voltage
- wall socket
Tap to Learn the Meanings!
- cable: A thick wire covered with plastic that carries electricity or signals.
- cord: A flexible wire that connects an electrical device to a power supply.
- electric shock: A sudden jolt felt when electricity passes through the body.
- mains electricity: The main source of electrical power from sockets in homes and buildings.
- plug: A device that connects an appliance to an electricity supply.
- pylon: A tall metal tower that supports electrical power lines.
- volt: The unit used to measure electrical force or potential.
- voltage: The strength or pressure of electricity flowing in a circuit.
- wall socket: A fixed outlet in a wall where a plug is inserted to get electricity.
Excellent! You’re learning key words about electricity and safety.
Conductors and insulators and mains electricity
In class you have made circuits with cells with voltages of 1.5 V or 3 V. ‘V’ stands for volt. A volt is a unit to measure the strength of electricity. We describe the strength of a supply of electricity as voltage. Cells with a voltage of 1.5 V or 3 V are safe to use.
You may have seen a pylon like the one in the photograph. Pylons carry electricity in cables (large wires) from where the electricity is made to where it is used in homes, factories and offices. The voltage of electricity carried by these cables is many thousands of volts!
Appliances like microwave ovens, electric kettles and power drills use mains electricity. Mains electricity has a much higher voltage than cells. In some countries it is 110 V and in other countries it is over 200 V.
At these high voltages, safety is very important. The parts of an appliance that you touch must be made from insulating material. The parts inside the appliance are made from conducting material so that electricity can pass through.
You know that metals, such as copper, iron and steel, are good electrical conductors. The parts of electrical appliances that let electricity pass through are made of metal. For example, metal is used for the pins in a plug. The pins allow electricity to travel from the wall socket, through the plug, and into an appliance such as a kettle or television.
When we handle the plug we only touch the cover. This is made of plastic, which is a good insulator.
Remember to never touch a bare electric wire, especially if your fingers are damp or sweaty.
Electric shocks
If mains electricity flows through your body you will get an electric shock. You will be badly burnt, your heart could stop beating and you could die.
Damaged electrical wiring is one of the main causes of accidents with electricity.
Plastic insulation often wears off the copper wires – you can get a shock if you touch the wires.
Never place an electric wire under a carpet. When people walk on the carpet the plastic wears off the copper wires. When bare copper wires touch each other, electricity flows between them and this can start a fire.
Never pull a plug out like this. This damages the cord and the wires become bare. If you handle the bare wires you could get an electric shock. Turn off the switch before you pull out the plug. Grip the plug, which is made of insulating plastic, to pull the plug out of the socket.
Be careful not to plug too many electrical devices into the same socket. This can overload the socket and could give you a shock if you touch the socket or one of the plugs. It could also cause a fire.
