Switch

In electrical engineering, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another. Switches turn electricity and electrical equipment on and off with ease, making a worker or lab tech's job simpler. They can shut off equipment in an emergency or provide instant access to power supplies when needed. There are two basic types of switches, electromechanical and electronic. Only electromechanical switches are discussed here 

In the simplest case, a switch has two conductive pieces, often metal, called contacts, connected to an external circuit, that touch to complete (make) the circuit, and separate to open (break) the circuit, this type of switch, known as a single-pole switch, is commonly used in the home for turning lights on and off.  The terms pole and throw are used to describe switch contact variations. The number of "poles" is the number of separate circuits which are controlled by a switch. For example, a "2‑pole" switch has two separate identical sets of contacts controlled by the same knob. The number of "throws" is the number of separate positions that the switch can adopt. A single-throw switch has one pair of contacts that can either be closed or open. A double-throw switch has a contact that can be connected to either of two other contacts, a triple-throw has a contact which can be connected to one of three other contacts, etc

The contact material is chosen for its resistance to corrosion, because most metals form insulating oxides that would prevent the switch from working. Contact materials are also chosen on the basis of electrical conductivity, hardness (resistance to abrasive wear), mechanical strength, low cost and low toxicity.

There are many different types of switches: toggle, rotary, push-button, "rocker", "pull-chain", slide, magnetic, mercury, timer, voice-activated, "touch-sensitive", and many others.

by: Valdy Septyano-112111227