In the diagrams shown below:
$(i)$ Name the type of current in two cases.
$(ii)$ Identify any one source for each type of these currents.
$(iii)$ What is the frequency of current in case $(ii)$ in India?
$(iv)$ Use above graphs to write two differences between the current in two cases.

Which sources produce alternating current?

In which of the following devices is an electric motor $NOT$ used?

State whether the following statements are true $(T)$ or false $(F)$.
$(a)$ An electric motor converts mechanical energy into electrical energy.
$(b)$ An electric generator works on the principle of electromagnetic induction.

$(a)$ Magnetic field lines of two bar magnets $A$ and $B$ are as shown below. Name the poles of the magnets facing each other.
$(b)$ Two magnetic field lines never intersect each other. Why?
$(c)$ How does the strength of the magnetic field at the centre of a current-carrying circular coil depend on the
$(i)$ radius of the coil,
$(ii)$ number of turns in the coil, and
$(iii)$ strength of the current flowing in the coil?

Electric motor converts mechanical energy into electrical energy.