Class 10 Science

Application of Heating Effect of Electric Current

  • Electric bulb, iron and fuse
  • Electric power

These notes are based on the chapter Electricity class 10 science of NCERT book and CBSE syllabus.

For exploiting the heating effect of electric current, the element of appliances must have high melting point to retain more heat. The heating effect of electric current is used in the following applications:

Electric Bulb

In an electric bulb, the filament of bulb gives light because of heating effect of electricity. The filament of bulb is generally made of tungsten metal, having melting point equal to 3380°C.

Electric iron

The element of electric iron is made of alloys having high melting point. Electric heater and geyser work on the same mechanism.

Electric Fuse

Electric fuse is used to protect electric appliances from high voltage, if any. Electric fuse is made of metal or alloy of metals, such as aluminium, copper, iron, lead, etc. In the case of flow of higher voltage than specified, fuse wire melts and protects the electric appliances.

Fuse of 1A, 2A, 3A, 5A, 10A, etc. are used for domestic purpose.

Suppose, if an electric heater consumes 1000W at 220V.

Then electric current in circuit `I = P/V`

Or, `I = 1000 W − 220 V = 4.5 A`

Thus, in this case a fuse of 5A should be used to protect the electric heater in the case of flow of higher voltage.

Immersion Rod

Immersion rod is used for heating water, especially during winter season. The immersion rod is made up of of very thick rod of metal which is coiled with a few turns at the middle. Free ends of the rod are connected to two terminals of electricity power supply. The immersion rod heats up and in turn heats water.


Geyser is composed of a cylindrical container along with a heating element. Geyser works in the same way as immersion rod but is much safer than immersion rod.

Some other devices which work on heating effect of electric current are: toaster, sandwich maker, soldering iron, etc.

Electric Power

The rate, per unit time, at which electrical energy is transferred by an electric circuit, is called electric power. The SI unit of power is the watt, one joule per second.

`1W = 1 text(volt) xx 1 text(ampere) = 1V xx 1A`

1 kilo watt or 1kW = 1000 W

Watt is a small unit. So, for the sake of convenience, consumption of electricity (electric energy) is generally measured in kilo watt.

Unit of electric energy is kilo watt hour (kWh)

`1 kWh = 1000 text(watt) xx 1 text(hour) = 1000 W xx 3600 s`

Or, `1kWh = 3.6 xx 10^6 text(watt second) = 3.6 xx 10^6  J`

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