ELECTRICITY , Class 7

ELECTRICITY

1.Current :

The flow of electricity is called current.When voltage is applied across a device, current begins to flow through the device.The greater the voltage across a device, the greater is the current through it.

2.Electric circuit :

A path along which an electric current can flow is called an electric circuit.The four main components of an electric circuit are- Battery(source), switch, a device consuming current(sink), conducting wire.

3.Circuit diagram:

A circuit diagram is a representation of a circuit using standard symbols for its components.

4.Symbols of components of electric circuit:

5.Resistance:

The electrical resistance of a piece of a material is a measure of the hindrance it creates to the flow of electric current.
Resistance depends on the
(a) material :- Copper and iron both are made of different materials. Their resistance will be different even though they have the same length and thickness.
(b) thickness :- More the thickness, less will be resistance.
(c) length :- More the length, more will be resistance.
A thin wire has a higher resistance than a thick wire.
A long wire has a higher resistance than a short wire.