(i) How does overload and short-circuit occur in an electric circuit ? Explain . What is the function of fuse during this situation ?
(ii) Mention two properties of magnetic field lines .

Explanation

(i) Overloading can occur when the live wire and the neutral wire come into direct contact.
This occurs when the insulation of wires is damaged or there is fault in the appliance.
In such a situation, the current in the circuit abruptly increases.
The joule heating that takes place in the fuse melts it to break the electric circuit, and prevents the electric appliances from possible damage.
(ii) No two field lines are found to cross each other.
The density of the magnetic field lines are more in their poles.
The magnetic field lines emerge from north pole and merge at south pole.
Inside the magnet, the direction of field lines is from its south pole to its north pole.
Thus the magnetic field lines are closed curves.