By considering how we control our appliances in our homes, we can understand how switches and variable resistors should be included in electrical circuits.
The resistance of an electrical component is a measure of its opposition to current.
A resistor opposes current by converting the electrical energy in a circuit into heat energy.
Variable resistors have many practical applications including volume controls, eg on a radio, and speed controls, eg on a mixer or a drill. There is usually a dial or sliding switch on the variable resistor which rotates or slides