Question

1) What is the function of earth wire in electrical instruments.
2) Explain what is short circuiting in electric supply.
3)What is the usual current rating of the fuse wire in the line to feed
(a)Lights and fans ?
(b) Appliances of 2kW or more power ?
All three questions together carry 3 marks .

Answer 1

1)Earth wire transfers any leakage of current in the connecting wires directly to the zero potential area that is earth....so that no damage or harm is been caused to us ..........it is necessary toearth the metallic appliances to prevent ourself from shocks .....ort injuries..
2)Short circuit is simply a low resistance connection between the two conductors supplying electrical power to any circuit. This results in excessive current flow in the power source through the 'short,' and may even cause the power source to be destroyed.
3)A. 5A is the usual current rating of the fuse wire in the line to feed lights and fans. b. 15A is the usual current rating of the fuse wire in the line to feed appliances of 2kW or more power.

Answer 2

i) Earth wire in electrical instruments saves us from electric shocks.All the electrical instruments must be properly earthed to ensure that any leakage of current to the metallic case of an electrical instrument does not give shock to the person

ii) When live wire and neutral wire comes in direct contact with each other is known as short circuiting. Short circuiting occurs when the insulation of wires is damaged and there is a fault in the electrical instrument.

iii)a) The usual current rating of the fuse wire in the line to feed in Lights and fans is 5A. 5A rating means that the fuse wire will melt if the current exceeds 5 amperes value.5A is used for running appliances of low rating such as bulbs, tube lights, fans, radio and T.V.

(b) The usual current rating of the fuse wire in the line to feed in Appliances of 2kW or more power is 15 A. 15 A is used for running appliances of high rating such as electric iron, geyser and refrigerator.

HOPE THIS WILL HELP YOU.