What constitutes a source of energy?

How can the pollution caused by fossil fuels be reduced?

Make a list of conventional and non-conventional sources of energy. Give a brief description of harnessing one non-conventional source of energy.

What do you suggest to overcome the problem of "limitation of sources of energy"? Mention any three suggestions for the effective use of energy.

State whether the following statement is true or false:
Solar cells and solar panels cannot be used in remote areas.

$(a)$ 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?