Ravi Raj

The earthing pin is bigger and longer also because, 1. Every electrical elements have some storing elements (i.e-capacitor). It might happen that when you remove the socket from electrical board, there may be some electrical energy stored in the device. next time when you again insert the socket this may cause a short circuit. SO the earth pin is made longer than other because it will come in contact before the other two pins and if there is any residual electrical energy left in the appliance it will tranfer it to the ground. 2. If the live wire comes in contact with the conducting body of the appliances it can damage other parts or can give a shock. It is bigger than the other two to dissipate the charge to ground faster . I think this will clear your doubt.