An electrical switch is any device used to interrupt the flow of electrons in a circuit. It is a device used for completing and breaking an electric current, or for changing the path of a current. Switches are essentially binary devices: they are either completely on (“closed”) or completely off (“open”). Electric switches are among the most common types of control devices and are in wide use wherever electricity is available.
In its simplest form, a switch consists of two contacts, one fixed and one movable. When the contacts are brought together, the switch and the circuit are closed and current flows through the circuit. Operating the switch to disconnect the contacts opens the circuit and stops the flow of current. This type of switch, known as a single-pole switch, is commonly used in the home for turning lights on and off. A switch may be directly manipulated by a human as a control signal to a system, such as a computer keyboard button, or to control power flow in a circuit, such as a light switch.
There are many different types of switches. Any switch designed to be operated by a person is generally called a hand switch, some of them are:
1. Toggle switches : are actuated by a lever angled in one of two or more positions. The common light switch used in household wiring is an example of a toggle switch.
2. Pushbutton switches : are two-position devices actuated with a button that is pressed and released.
3. Selector switches : are actuated with a rotary knob or lever of some sort to select one of two or more positions.
4. A joystick switch : is actuated by a lever free to move in more than one axis of motion.