Wire wound resistors are used where the resistor has to dissipate a lot of heat. Some resistors are designed to change value when heated. They are called thermistors and are used in temperature measuring circuits. Some resistors change in value when exposed to light. They are called light-dependent resistors.
Variable resistors are also available.
These can usually be operated by means of a knob or a slide on the control panel. Inductors and capacitors 2.3 Simple inductors are made up of tightly wrapped multiple wire loops. Real differences arise when the currents through them vary in time. Capacitors are made of two conductive plates separated by a very thin insulating film. Constant current is unable to flow through them, but charge can be stored on the metal plates.