Question

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.

Answer 1

(a) The underlying principle in the working of a dynamo is that changing magnetic flux in a conductor induces emf.  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 qualities shown by the teacher are: helpful and responsible as a teacher, and knowledgeable. The qualities shown by Ram are inquisitive and observing.