$(i)$ Write the values of the following physical quantities in connection with domestic power supply in our country: $(a)$ potential difference between live wire and neutral wire.
$(b)$ frequency of $AC$.
$(ii)$ Explain the role of the following as safety measure in domestic electric appliances/circuits:
$(a)$ earth wire
$(b)$ fuse.

(N/A) $(i)$
$(a) 220 \ V$
$(b) 50 \ Hz$
$(ii)$
$(a)$ Earth wire: The earth wire is a thick metal wire connected to a metal plate buried deep into the earth. It is used as a safety measure for appliances with a metallic body,$e.g.$,toasters,etc. The metallic body is connected to the earth wire,which provides a low-resistance conducting path for the current. It ensures that any leakage of current in the metallic body keeps its potential equal to that of the earth,preventing the user from getting a severe electric shock if touched.
$(b)$ Fuse: It is a piece of wire made of an alloy with a low melting point. If a current larger than the specified value flows through the circuit,the temperature of the fuse wire increases and it melts. This breaks the circuit and prevents the flow of an excessively high electric current in the device. In this way,a fuse of proper rating protects the appliance and the circuit from damage.