The solarconstant is the flux (energy per time per area) in radiationfrom the sun at the distance of the earth ( R = 150 million km) andhas the approximate value 1350 W/m2. (a) What is the sun'stotal power output in Watts? (b) About half the sun'soutput is in the visible range, with average wavelength about 550nm. How many visible photons are coming out of the sun per second?(c) Estimate the number ofvisible photons hitting your face each second if you stand facingthe sun directly (A˜15cm x 20 cm).

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