Question

(a)What is the role of a plane mirror and a glass sheet in a solar cooker.
(b) Why is energy of water flowing in a river considered to be an indirect form of solar energy ?
(c) Why is nuclear fusion reaction considered better.

Answer 1

(a) Plane mirror reflects solar light to fall on the glass sheet of the solar cooker. Plane glass plate does not allow the infrared or heat radiation entered in the box to go outside the box. Thus, the box becomes hot. The phenomenon is known as the greenhouse effect.
(b) Solar energy evaporates water in rivers, lakes and oceans. These water vapours are converted into clouds (K.E. + P.E.). The clouds give rise to rain and hence water flows in rivers. Thus, energy of flowing water in the form of kinetic energy is the indirect form of solar energy.
(c) Nuclear fusion reaction gives rise to energy which is pollution-free.