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Electric Current and Its Effects-CBSE CLASS 7


The most convenient source of energy is electricity. Electricity is very used to run many electrical appliances  such as an electric bulb, television, a stereo system, refrigerator, washing machine, computers, etc
We can't think life without electricity.
Electricity is generated at power stations from where it is brought to our homes through the thin wire and electric poles networks or underground cable.

Electric current

Electric current is flow of electricity through a conductor (wires, cables).
Electricity and electric current are both used for same sense.
There is another source of electricity, i.e. electric cell or battery. That is used to stores electrical energy in form of chemical energy.
To obtain electric current from a cell / battery, It has to connect into a circuit.

Electric Circuits

Electric Circuit is the continuous conducting path consisting of wires, bulb, switch, etc between the two terminals of a cell or battery along with an electric current flows.

Circuit Diagram

A circuit diagram shows, How the various components in an electric circuit have been connected by using the electrical symbols of the components.

Electric Cell and Battery

It is the common source of electricity to run the number of devices, e.g. electric clocks , watches, toys and radio etc., is an electric cell.

The cell provides very less electricity as compared to that provided by the electric supply line, e.g. in the case, a single electric cell which generates only 1.5 V of electricity, whereas electricity from the power station is supplied to our home at very high voltage of 220 V.

When we connect two or more cells to obtain higher voltage is known as battery.Thus battery indicates group of cells joined together in the series.

If positive terminal of one cell is joined with the negative terminal of the other cell, then the cells are said to be joined in series

Two or more cells connected in side by side such a manner that all postive terminal and all negetive terminal joint together respectively are said to be joined in parallel. This combination is also called battery.

When positive terminal of one cell in contact with the positive terminal of the other cell or negative terminal of one cell in contact with the negative terminal of the other cell. This combination is called parallel combustion. This is not serve the purpose of battery.

An open circuit means that there is a break (or gap) in the circuit and electricity can not flow in this circuit. whereas a closed circuit means that it is a complete circuit and electricity passes through it.


Rasistance is the property of material due to which it opposes the passage of current through itself is known as its resistance.

Heating Effect of Electric Current

When an electric current is passes through a conductor (wire) the conductor becomes hot after some time and produce heat. This effect is called heating effect of current

Devices Which Work on Heating Effect of Electric Current:

Electric bulb is a best example of a device which works on heating effect of electric current. The filament of bulb is made of tungsten. Tungsten has very high melting point and high rasistance that is the reason it is used in electric bulb.Argon gas is filled inside the bulb to prevents the filament from catching fire. Electric iron, geyser, toaster, water heater etc. are some other devices which work on heating effect of electric current.

Heating effect of current are depent on following

The amount of heat generated in a wire due to heating effect of current .Which depends on two factors:
(1) Resistance of wire (rasistance of wire depends on material of wire , length of wire and thickness of wire).
(2) Magnitude or amount of current passed through the wire.
(3)time period of elecricity flow through wire .

Electric fuse

Electric fuse is a safety device used to prevent damage to an electrical circuit when excessive current flows through it.
The electric fuse has a thin wire with a low melting so they melt first in electric circuit when high electric current passes through the circuit.
It works on the principle of heating effect of current.

Magnetic effect of current

When electricity passes through a wire, the current-carrying wire behaves like a magnet. This effect of current is called the magnetic effect of current.
The magnetic effect of current is utilised in making electromagnets, electric bells, telephone instruments, electric fans, electric motors, loudspeakers and toys etc


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