Two identical circular coils P and S are placed coaxially, a few millimetres apart. Coil P is connected to a battery through a key K, while coil S is connected to a sensitive galvanometer.
(i) State Lenz’s law.
(ii) Describe and explain the observations in the galvanometer when the key K is: (a) suddenly closed, (b) kept steadily closed, and (c) suddenly opened.
(iii) Using the principle of conservation of energy, justify the direction of the induced current in coil S at the instant the current in coil P is increasing.