PHYSICS · Multi-part · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
Four different surfaces—(A) a cavity with a small pin-hole opening, (B) a sheet of lamp-black, (C) a red cotton cloth, and (D) a highly polished silver plate—are all kept at the same temperature in identical surroundings. Study them with respect to their ability to act like a blackbody.
(i) Arrange the surfaces in decreasing order of their expected absorptive power aλ for visible radiation.
(ii) Identify which surface best approximates an ideal blackbody and justify your choice on the basis of surface properties.
(iii) Briefly describe one experimental method by which you could verify the ranking given in part (i) using readily available laboratory apparatus.