Switch

Switches is a mechanical tool used in electronics to open or close a circuit. Many of switches requires mechanical forces to operates them. There are 3 types of switches that is

(i) Push Switch

(ii) Toggle Switch

(iii) Slide Switch

• 
  Push switch
• 
  Toggle Switch
• 
  Slide Switch

Switch Operation

A switch that is switched 'on' / 'closed' allows current to passed thru meanwhile a switch that is switched 'off' / 'opened' stops current from passing thru it.

Opened Switch, I ≠ 0 . Circuit is closed

Closed Switch, I = 0 . Circuit is opened

Types of Switch

There are 4 main types of switches that are shown in table below: As you noticed, there are 2 re-occuring termsn namely: Pole and Throw.

A Pole simply means how many circuits the switch controls. Single Pole controls one circuit with one switch, Double Pole controls two separate circuits with one switch.

A Throw simply refers to how many ON positions the switch has. Single Throw have one ON position, Double Throw have two ON position

Switches	Symbol	Operation
Single Pole Single Throw		Functions like typical ON/OFF switch
Single Pole Double Throw		Switch can only switch ON any circuits at the single moment only
Double Pole Single Throw		Switch can control 2 separate circuit on the single moment
Double Pole Double Throw		Switch can control 4 separate circuits on the single moment (with double operational modes)

Reference