You know that Energy exists in various forms such as Mechanical energy, Heat energy, Chemical energy Electrical energy, Light energy, and Nuclear energy. In our daily life, we use many devices where electric energy is converted into heat energy. Your parents would have prevented you to touch an incandescent lighted bulb. It may be very hot and your hand may get burnt. Let�s do an activity to understand the heating effect of Electric current.
Take an electric cell, a bulb, a switch, and a connecting wire. Make an electric circuit as shown here. First, consider the switch in the OFF position. What do you see? The bulb is not glowing. Touch the bulb. You will find it is cold. Now, set the switch in the ON position and let the bulb glow. Again touch the bulb. Now you will find that the bulb is hot. The bulb was not hot when the switch was OFF. When you switch ON the bulb, it becomes hot.
Now you know, that it is the electric current that heated the bulb. The filament of an electric bulb gets heated to such a high temperature that it starts glowing.
Heating Effect of Electric Current: When an electric current passes through the filaments of the bulb, it produces heat and the bulb becomes hot. This property is called the heating effect of electric current.
James Prescott Joule was the first scientist who studied the heating effect of electric current. In place of the bulb, you can use a piece of nichrome wire to understand the heating effect of electric current.
Take about 10cm long piece of nichrome wire, two nails, an electric cell, and a switch. Tie the nichrome wire between the nails. Touch the wire. What do you find? It is cold. Now, switch on the current in the circuit by turning the switch to the ON position. Touch the wire. It gets hot after passing an electric current through it. The wire may or may not emit any kind of light. This is the heating effect of electric current.
You might have seen an electric room heater or an electric heater used for cooking. These appliances have coils of wire called heating elements that produce heat on passing current. As current flows through these appliances, the heating element inside turns bright �orange red� in color. This is because a huge amount of heat is produced when current flows through the coil.
Different appliances have different types of heating elements. The type of element depends on the function of the appliance. The amount of heat produced in a wire depends on its material, length, and thickness. Thus for different requirements, the wires of different materials and different lengths and thicknesses are used.
Application of Heating Effect of Electricity
You have studied about Heating Effect of Electric Current: according to which When an electric current flows through the filament of a bulb, it generates heat and so the bulb becomes hot and starts emitting light.
In a bulb, due to the heating effect of electric current not all electrical energy is utilized, some part of the electrical energy is always wasted in the form of heat. On the other hand, CFLs are very economical and energy-efficient as compared to bulbs. As CFLs do not make use of filaments and heating effect of electric current. In CFL�s light is produced by making use of two electrodes.
The fluorescent coating inside the CFL makes the light brighter. So, we should use CFLs instead of ordinary bulbs to minimize the wastage of electricity. Can you think of any electric appliance where the heating effect of the electric current is used?
There are a large number of electrical appliances which work on the phenomena of the heating effect of electric current. For example, electric room heater, electric roti maker, electric iron, toaster, electric stove, hairdryer, immersion water heater, food warmer, electric coffee maker, electric rice cooker, and geyser.