Q22 of 22 Page 344

What is Joule’s heating effect? How can it be demonstrated experimentally? List its four applications in daily life.

Joule’s heating effect : The Joule's law states that the quantity of heat produced in a resistor is directly proportional to:

(i)The square of current for a given resistance,


(ii)The resistance for a given current,


(iii)The time for which the current flows through the resistor,


⇒ H = I2Rt.


A simple experiment to demonstrate Joule’s heating effect is that if we switch on the electric bulb for a long period of time than it becomes hot.


Four applications of Joule's heating effect in daily life are:


(i) Electric fuse is a safety circuit devices work on this principle.


(ii) Electric iron we use to iron our clothes works on this principle.


(iii) Electric kettle used to boil water also works on this principle.


(iv) Electric toaster to make bake breads works on the same principle.


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How will you conclude that the same potential difference (voltage) exists across three resistors connected in a parallel arrangement to a battery?

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Three bulbs each having power P are connected in series in an electric circuit. In another circuit another set of three bulbs of same power are connected in parallel to the same source.

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ii. Now let one bulb in each circuit get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.

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