(i) It is used in factories and cranes to lift heavy iron ingots and steel scraps from one place to another.
(ii) Used in hospitals to remove iron splinters from the eyes of the patients.
(iii) Used in electric bells, relays, electric switches etc.

No, if two magnetic lines of force intersect then there will be two tangents and hence two directions of the magnetic field at the point of intersection. This is not possible.

First law: Whenever there is a change in magnetic flux linked with a coil, an electric current is induced. The induced potential difference lasts so long as there is a change in the magnetic flux linked with the coil.
Second law: The magnitude of the induced current is directly proportional to the rate of change of magnetic flux linked with the coil

(i) If a current is passed through coil B by plugging the key, the needle of the galvanometer instantly jumps to one side and just as quickly returns to zero, indicating a momentary current in coil - A (As the current in the coil B changes, the magnetic field associated with it also changes).
(ii) If the current is stopped by removing the plug from the key: The needle of the galvanometer in coil - A momentarily moves, but to the opposite side. It means that now the current flows in the opposite direction in coil - A.

It is a step down transformer. So that rectified DC voltage is equal to battery voltage, hence it can work on mains as well as on battery.

(i) The cost of generation of AC is less than the cost of generation of DC.
(ii) AC can be easily converted into D.C.
(iii) Only alternating voltage can be stepped up or stepped down by using a transformer.
(iv) AC can be transmitted to distant places without much loss of electric power than DC.