Question

what is the function of earth wire in electrical instrument?

Answer 1

Earth wire helps in preventing the device from unwanted short circuit current or surge current.
It also helps protect the device from lightning during use of outdoor activities. It carries the lightning surge current to ground.
it is needed to pass the unwanted leakage current to the ground for safety and if it is connected already, then you won't be shocked while touching it.

Answer 2

to protect from the electrical shock, charge is transferred to the earth by using a earth wire in the electrical instruments at home. it's do so we cannot get any electrical shock. sometimes u may have seen u got a current by touching cpu. it's because earth wire is not fitted with the cpu. so earth wire is essential for earthing.