question_answer

   (i) Name the device used to convert (a) solar energy into heat, and (b) solar energy into electricity. (ii) Explain the principle of working of a windmill.

Answer:

                  (i) (a) Solar energy into heat: Solar cooker. (b) Solar energy into electricity: Solar cell. (ii) The wind rotates the blades of the windmill. This, in turn, rotates the connecting rod (shaft) and the crank (u-bend) moves up and down. Since the pump rod is connected to the crank, the pump rod of the water pump also moves up and down and lifts the water from the well or flooded mine. Thus, the rotational movement of the blades of the windmill is used to drive a large number of machines.