Use of Electricity
What happens when we switch on the light in a room? The light comes on, of course. But how does current flow? Where is the circuit?
The electrical supply comes from the power station, which is usually a long way from your house. The electrical cables coming to your house goes to the light switch on the wall. It is like a battery in some ways, with two contact points. A wire is connected to each of these points. The two wires then go to the lamp on the ceiling.
When the switch is closed, current flows through one wire to the lamp, lights it up, and flows back through the other wire. This completes the circuit.
What happens when we switch on an electric kettle full of water? The water starts boiling. Again, how does current flow? Where is the circuit?
It is quite similar to switching on light on the ceiling. One end of a cable is plugged into a mains socket on the wall. The mains socket is an electrical power supply. It has two contact points that supply the electricity. The other end of the cable is connected at the kettle.
When the switch at the socket is on, current flows through one wire in the cable to the kettle. The current goes into the kettle and heats up the water. The current then leaves, goes through a different wire in the cable, and return to the other contact point on mains socket.
The picture below shows the main parts in a motor. When it is connected to a battery, it rotates.
An example where a motor is used is the electric fan. The electric fan normally has a cable that plugs into the mains socket on the wall. When the switch on the mains socket is on, current flows through one wire in the cable, and goes into the motor in the fan. The motor then rotates the fan.
The current comes out through a different wire in the cable and return to another contact point on the mains socket.
