$(a)$ Name the type of electric current generated by most of the power stations in our country.
$(b)$ Why is it preferred over the other type?
$(c)$ State the frequency of the power supply generated in India.

$(a)$ When do we state that an electrical appliance is earthed? Mention the function of the earth wire in electric lines. Why is it necessary to earth electric appliances having a metallic body?
$(b)$ Explain what is short-circuiting and overloading in an electric supply.

$(a)$ $A$ coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is:
$(i)$ pushed into the coil with its north pole entering first?
$(ii)$ withdrawn from inside the coil?
$(iii)$ held stationary inside the coil?
$(b)$ Name the above phenomenon and mention the name of the scientist who discovered it. State the law that relates the direction of current in the coil with the direction of motion of the magnet.

$(a)$ Define electromagnetic induction.
$(b)$ Two coils $P$ and $S$ are wound over the same iron core. Coil $P$ is connected to a battery and a key,and coil $S$ is connected to a galvanometer. Draw a suitable diagram of this arrangement and write your observations when:
$(i)$ current in the coil $P$ is started by closing the key.
$(ii)$ current continues to flow in coil $P$.
$(iii)$ current in coil $P$ is stopped by removing the key.
Explain the reason for such observations.

Why do iron filings arrange themselves in a certain pattern around a magnet?

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