State two characteristics which a source of energy must have.

Select the renewable and non-renewable sources of energy from the following —

(a) Coal
(b) Wood
(c) Water
(d) Diesel
(e) Wind
(f) Oil

State the energy transformation in the following —

1. electricity is obtained from solar energy.
2. electricity is obtained from wind energy.
3. electricity is obtained from hydro energy.
4. electricity is obtained from nuclear energy.

The conversion of part of energy into an unuseful form of energy is called .