Fuse:

An electric fuse is a safety device which is used to limit the current in an electric circuit.It safeguards the circuit and the appliances connected in that circuit from being damaged.

 

http://www.veloxswitchgears.com/images/electrical-fuse250x250.jpg

Switches

A switch is an on-off device for current in a circuit (or in an appliance) .It is connected in the live wire.

 

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Series and Parallel Circuit

                        Series and Parallel Circuit   

               

Source of the Image - http://www.instructables.com/id/Operation-Game/step16/About-Parallel-and-Series-Circuits/