(a) Why are thick wires used to carry current in high power appliances such as electric heaters and radiators?
(b) Name a device used to protect the electric circuits from overloading and short circuits.
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(a) High power appliances such as heaters and radiators draw a large current. Since the resistance of a wire is inversely proportional to its area of cross-section, a thick wire has a large area of cross-section and hence a low resistance. Therefore the heat produced (H = I2Rt) in a thick wire is small and it can carry a heavy current without getting over-heated, so there is no danger of the insulation burning or of a fire.
(b) A fuse (or a miniature circuit breaker, MCB) is used to protect the electric circuits from overloading and short circuits.