The pressure exerted by electromagnetic radiation in thermal equilibrium (called black body radiation) is P =  1 K T4, 3 u where Ku = 7.56 × 10-16 J K-4 m-3.

(a) At what temperature is the radiation pressure equal to 10-8 Pa. (In the laboratory 10-8 Pa is a high vacuum.)

(b) Estimate the radiation pressure at the surface of the sun. (See Table 1.1.)

(c) Estimate the radiation pressure at center of the sun.