question_answer

Direction: Q.16 to Q.20

Current can be induced not only in conducting coils, but also in conducting sheets or blocks. Current is induced in solid metallic masses when the magnetic flux threading through them changes. Such currents flow in the form of irregularly shaped loops throughout the body of the metal. These currents look like eddies or whirlpools in water so they are known as eddy currents. Eddy currents have both undesirable effects and practically useful applications. For example, it causes unnecessary heating and wastage of power in electric motors, dynamos and in the cores of transformers.

Read the given passage carefully and give the answer of the following questions:

The working of speedometers of trains is based on:

A) wattles currents              

B) eddy currents

C) alternating currents  

D) pulsating currents