An electric battery is a device consisting of one or more electrochemical cells that convert stored chemical energy into electrical energy.

Switching devices are used to close (make) or open (break).

Tungsten-based alloys are used because tungsten has the highest melting point and the lowest thermal expansion coefficient of any metal.

The units of potential difference are the volt (V) which is defined as one joule per coulomb.

Red indicates the secondary live wires in a 220-volt circuit. 

Copper is good conductor of electricity because it 'conducts' the electron current of electrons quite easily.

Material needed for conductor should be cheap as wires are used extensively in almost every appliance. That is why silver can't be used to make wires.

It is a coil of wire made of a special material called nichrome which becomes very hot when current is passed.

An electric bell works when an electrical current flows through an electromagnetic coil.

Insulators are non-conducting materials with few mobile charges.

A relay is an electromagnetic switch.

The first electric cell was developed by an italian scientist Luigi Galvani.

Solar cells convert light energy into electric energy.

Plastic does not normally conduct electricity.

Graphite is not a great conductor of electricity, but it does allow electric current to flow