Draw a labelled diagram to explain the principle underlying the working of an electric generator.

38 Explain the principle and working of an electric motor with the help of a diagram. What is the function of a split–ring commutator ? 39 A coil of copper wire is connected to a galvanometer. What would happen if a bar magnet is
(i) Pushed into the coil with its north pole entering first?
(ii) Pulled out of the bar magnet?
(iii) Held stationary inside the coil? 41 What is the function of an earth wire? Why is it necessary to earth the metallic appliances? 42 Explain what is short-circuiting and overloading in an electric supply.