Mention three advantages and three disadvantage of producing hydroelectricity by building dams on rivers.
(b) given reason for the following
(i) A solar cooker box is covered with a glass plate
(ii) A solar cooker box is painted black from inside

Explanation

(b) (i) Glass plate increases the inside temperature of the solar cooker due to the green house effect of infrared rays of sun
(ii) Black colour absorbs the heat energy quickly.