Ram is a student of class X in a village school. His uncle gifted him a bicycle with a dynamo fitted in it. He was very excited to get it. While cycling during night, he could light the bulb and see the objects on the road. He however, did not know how this device works. He asked this question to his teacher. The teacher considered it an opportunity to explain the working to the whole class. Answer the following questions :

(a) State the principle and working of a dynamo.

(b) Write two values each displayed by Ram and his school teacher.

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Solution

(a) A dynamo works on the principle of electro magnetic induction.

A dynamo includes a coil attached to a small turbine fitted with a plastic cap.

The coil is placed in a magnetic field. When the plastic cap comes in contact with moving tyres of the bicycle, the coil placed between the poles of a magnet rotates, thus, the flux through the coil changes continuously. This induces a current in the coil which is connected to a bulb which lights up.

As long as the bicycle is moving, the coil keeps on rotating, and hence, the flux keeps on changing. At a steady rate, we get a steady current and hence a light of steady intensity.

(b) The values shown by Ram :
(i) Positive approach
(ii) Curious to know the scientific reasons behind the working of the dynamo.

The values shown by the school teacher :
(i) Positive attitude towards queries.
(ii) Helping other students also in understanding the concept.

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