Electricity
Resistance is the ability of a substance to "slow" the flow of the current, that is, to reduce the rate at which the charge flows through the substance. If an electric voltage of 1 volt maintains a current of 1 ampere through a wire, the resistance of the wire is 1 ohm - this is called Ohm's law. When the flow of current is opposed, energy gets "used up" which means it is converted to other forms (such as light, heat, sound or movement)