(a) What is the purpose of a switch in a circuit?

(b) Why is the switch put in the live wire?

(c) What precaution do you take while handling a switch?

(a) A switch is an on-off device for current in a circuit (or in an appliance). It is connected in the live wire.

(b) The switch is put in the live wire because when the switch is in 'on' position, the appliance gets connected to the high potential point through the live wire and current flows in the appliance, the circuit is complete and the neutral wire provides the return path for the current. In the off position of the switch, the circuit is incomplete and no current reaches the appliance through the live wire. It is now safe to carry out repairs in the appliance, if required.

On the other hand, it is unsafe to connect a switch in the neutral wire. In the 'off' position of the switch the appliance remains connected to the high potential terminal through the live wire, although no current flows through the appliance because the return path is incomplete. However, it is not safe to carry out repair work in this condition because on touching the live wire in the appliance the current will pass through the body of the person and he may get a fatal shock. Moreover, if due to some fault, live wire touches the metallic body of the appliance then on touching the appliance the person may get a fatal shock.

(c) A switch should never be touched with wet hands. If water reaches the live wire, it forms a conducting layer between the hand and the live wire of the switch due to which a current passes to the hand through it and the person may get a fatal shock.