Household electricity
In domestic devices, energy is transferred from the batteries or ac mains to the energy of motors and heating devices.
Switches
One-way switch
This type of switch is used to switch a light from just one place e.g. beside a door.
The switch operates as a make or break switch, because:
- when it is turned on, the two terminals are connected and current flows;
- when it is turned off, the contact between the two terminals is broken and current does not flow.
Two-way switch
A two-way switch can be used to control a light from two locations inside a house e.g. on a staircase or in a long hallway.
They are also used in school corridors so that lights can be switched from both ends of a corridor.
Two, one-way switches are joined by wires so that flipping either switch can turn the light on or off.
When both switches are up i.e. both at L1, the circuit is complete, current flows and the lamp lights.
If one of the switches, at the top or bottom of the stairs, is switched down to L2, the circuit is broken, current stops flowing, and the lamp is off.
With the switches in the positions shown in the above diagram the lamp would be off.