Question

1. (a) What is the function of
(i) live wire
(ii) ​​neutral wire
(iii) earth wire
(b) what is overloading and short circuiting.

Answer 1

The live wire carries current to the appliance at a high voltage.

The neutral wire completes the circuitand carries current away from the appliance.

The earth wire is a safety wire and connects the metal case of the appliance to the earth. This stops a fault making the case of the appliance live.

Short circuiting: Short circuiting occurs when naked live and neutral wires touch each other. In such a case, the resistance of the circuit becomes very less. Now, according to Ohms law, current is inversely proportional to resistance. Thus, the lowering of resistance of the circuit raises the current to a significant amount. As a result, the wires become hot and a spark is caused by Joules heating effect of current. This situation is known as short circuiting.

Overloading: A large amount of current is withdrawn from the circuit, when a large number of electrical appliances of high power-rating are switched on at the same time or connected in a single multi-plug. This situation is called overloading.