How many times does an $AC$ electric current with the frequency $50\, Hz$ change its direction in one second?

$(i)$ 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.

Explain why a fuse should be joined with the live wire and not with the neutral wire in a domestic circuit.

The magnitude of an $AC$ voltage used in India is $......$ and its frequency is $......$.

Differentiate between overloading and short-circuiting.

Name three colours used and names of the wires used in household wiring.