Process of the working of an electric bell

1. The switch is pressed and current flows through the circuit.
2. The electromagnet is powered and generates a magnetic field that attracts the iron strip towards it.
3. The striker strikes the gong (bell).
4. When the striking arm strikes the gong, the contact is broken and the current stops flowing through the circuit.
5. This causes the electromagnet to lose its magnetic field.
6. The connected spring arm returns the striker to its original rest position.
7. The contact is restored and current flows through the circuit (provided the main switch is still pressed).

When two north poles are approached together, the magnetic field lines repel each other and the two magnets experience a repulsive force. The same occurs if two south poles are approached together.

Like poles repel each other

The direction of magnetic lines of force of a bar magnet is from north to south pole outside the magnet as shown in figure below.