$(a)$ What is the function of an earth wire in electrical instruments? Why is it necessary to earth the metallic electric appliances?
$(b)$ Explain what is short-circuiting and overloading in an electric supply.
$(c)$ What is the usual capacity of the fuse wire in the line to feed:
$(i)$ lights and fans?
$(ii)$ appliances of $2 \,kW$ or more power?

(N/A) The earth wire provides a low-resistance path for the current to flow to the ground in case of any leakage,preventing electric shock to the user. It is necessary to earth metallic appliances to protect the user from accidental electric shocks if the live wire touches the metallic casing.
$(b)$ Short-circuiting: This occurs when the live wire comes into direct contact with the neutral wire,causing a sudden,massive increase in current due to zero resistance in the path.
Overloading: This occurs when too many electrical appliances are connected to a single socket or circuit,drawing current beyond the capacity of the wires,which can lead to overheating.
$(c)$ $(i)$ For lights and fans,the fuse capacity is $5 \,A$.
$(ii)$ For appliances of $2 \,kW$ or more,the fuse capacity is $15 \,A$.