(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] If the live and neutral wires come in contact directly or indirectly due to defective or damaged wiring in an appliance, the resistance of the circuit becomes almost zero and a huge current flows through the circuit. This is called short circuiting. Overloading occurs when many appliances are switched on at the same time and they draw a large current [exceeding 5 A for lighting circuit and 15 A for heating circuit ] from the mains, or due to an accidental hike in the supply voltage.
Both short circuiting and overloading cause overheating of the wires which may result in spark or fire or damage the appliances. This can be avoided by using an electric fuse in live a wire. A fuse is a current-conducting wire made of pure tin or of an alloy of copper and tin, has low resistance, and a low melting point. a fuse is rate for either 5 a or 15 A. When a current more than the rated value flows through it, the fuse wire melts and breaks the circuit. This, it protects the appliances from getting damaged during short circuit or overloading.
ii] Two properties of magnetic field liens :
a] They originate from the north pole and enter into the south pole of the magnet.
They are closed and continuous curves.