29. (a) The upward force supplied by radiation pressure in this case (Eq. 33-32) must be equal to the magnitude of the pull of gravity (mg). For a sphere, the “projected” area (which is a factor in Eq. 33-32) is that of a circle A= πr2(not the entire surface area of the sphere) and the volume (needed because the mass is given by the density multiplied by the volume: m= ρV) is 34/3Vrπ=. Finally, the intensity is related to the power
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This note was uploaded on 06/03/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.