What is the function of an earth wire? Why is it necessary to earth metallic appliances?
The earth wire is a safety wire with green insulation that is connected to a metal plate buried deep in the earth near the house. It is an essential component of domestic electric circuits.
The main function of the earth wire is to provide a low-resistance conducting path for the current. This path allows any leakage of current to flow safely into the earth.
It is necessary to earth metallic appliances like electric press, toaster, table fan, and refrigerator because these appliances have metallic bodies. If there is any leakage of current to the metallic body, the earth wire ensures that the potential of the metallic body remains equal to that of the earth.
This safety measure prevents the user from getting a severe electric shock. Without proper earthing, if a person touches a metallic appliance with leaked current, they could receive a dangerous shock.
Thus, the earth wire serves as a crucial safety device in domestic circuits, protecting users from electrical hazards.
Explanation
The textbook explains that the earth wire (with green insulation) is connected to a metal plate deep in the earth and serves as a safety measure for appliances with metallic bodies. The key mechanism is that it provides a low-resistance conducting path for current, ensuring that any leakage current to the metallic body keeps its potential equal to that of the earth, thereby protecting users from severe electric shocks.