Problem #4: Give and expression for the solid angle, 92, of a square seen from point 0. Problem #5: The surface of the sun has an effective blackbody radiating temperature of 5780 K. 0 h L/2 L/2 L/2 L/2 (a) What percentage of the solar radiant emission lies in the visible range = 0.4-0.7 m? (b) What percentage is in the ultraviolet range? (c) At what wavelength and frequency is the maximum energy per unit wavelength emitted? (d) What is the maximum value of the solar hemispherical spectral emissive power?