Question

The following diagram in figure shows a fixed coil of several turns connected to a centre zero galvanometer G and a magnet NS which can move in the direction shown in the diagram. Describe the observation in the galvanometer if the magnet is kept still after it has moved into the coil.

Answer 1

When a magnet is moved closer to the current carrying coil it will generate electricity as the coil moves through the magnetic field. As the magnet is moved, there will be an induced electro-motive force (EMF) which can cause a current in the coil. Once the magnet stops moving, the current will go to zero.
Hence, when a galvanometer is connected to the circuit, there will be deflection due to the flow of electricity. As the magnet is moved toward the coil of wire, the needle of the galvanometer moves one direction. As the magnet is moved away from the coil of wire, the needle of the galvanometer moves the opposite direction. If the magnet is moved faster, the magnitude of the deflection increases.
When the magnet is moved towards or away from the coil, the pointer or needle of the Galvanometer, which is basically a very sensitive center zeroed moving-coil ammeter, will deflect away from its center position in one direction only. When the magnet stops moving and is held stationary inside with regards to the coil the needle of the galvanometer returns back to zero as there is no physical movement of the magnetic field.