State whether the following statements are true or false.
$(a)$ The magnetic field at the centre of a long circular coil carrying current consists of parallel straight lines.
$(b)$ $A$ wire with green insulation is usually the live wire of an electric supply.

$(a)$ 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?

The most important safety method used for protecting home appliances from short circuiting or overloading is

State one main difference between $AC$ and $DC$. Why is $AC$ preferred over $DC$ for long-range transmission of electric power? Name one source each of $DC$ and $AC$.

Connecting too many appliances to a single circuit often leads to an increase in electric current. What is this phenomenon called?

$(i)$ The given figure shows a domestic electric circuit. Study this circuit carefully. List any two errors in the circuit and justify your answer.
$(ii)$ Give one difference between the wires used in the element of an electric heater and in a fuse:
$(iii)$ List two advantages of parallel connection over series connection.