CBSE Class 11-science Answered
(i) The body having a large reflectivity (or bright surface) is a poor absorber of heat radiations. Poor absorbers are poor radiators. Therefore, a body with a large reflectivity is a poor emitter.
(ii) Brass is a good conductor of heat. When we touch the brass tumbler, heat is quickly transferred from the fingertips to the tumbler. Thus, we feel cold while touching the brass (or any other) tumbler on a chilly day.
(iii) The temperature of the red hot iron in the oven is given by . However, when the iron is taken out in the open (To), then its radiant energy is given by . Therefore, the pyrometer will measure a low value for the red hot iron in the open.
(iv) The atmosphere acts as a blanket over the Earth and does not allow its heat to be radiated during the night.
(v) Because steam contains more heat in the form of latent heat (540 cal/g) than water.