(a) A student wants to use an electric heater, an electric bulb and an electric fan simultaneously. How should these gadgets be connected with the mains? Justify your answer giving three reasons.

(b) What is an electric fuse? How is it connected in a circuit?

(a) The gadgets (electric heater, electric bulb, and electric fan) should be connected in parallel with the mains.

Justification (Three Reasons):

1. Independent Operation: In a parallel circuit, each appliance has its own independent switch. If one appliance is switched off or fails, the other appliances continue to function normally.
2. Constant Voltage: Each appliance receives the full mains voltage (typically $220\text{ V}$), which is necessary for them to operate at their rated power.
3. Appropriate Current Distribution: Different appliances have different resistances and require different currents to operate. In a parallel connection, the current divides among the appliances according to their requirements ($I = V/R$), whereas in series, the same current would flow through all, preventing them from working efficiently.

(b) Electric Fuse: An electric fuse is a safety device consisting of a wire made of a material with a low melting point and high resistivity (such as an alloy of lead and tin). It protects electrical circuits and appliances from damage due to excessive current (overloading or short-circuiting) by melting and breaking the circuit.

Connection: It is always connected in series with the live wire before the current enters the domestic appliances.