The radiant energy from the Sun that reaches Earth's orbit is 1.35 kW/m2.


(a) Even when the Sun is directly overhead and under dry desert conditions, 25 percent of this energy is absorbed and/or reflected by the atmosphere before it reaches Earth's surface. If the average frequency of the electromagnetic radiation from the Sun is 5.50 1014 Hz, how many photons per second would be incident upon a 1.1-m2 solar panel?

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(b) Suppose the efficiency of the panels for converting the radiant energy to electrical energy and delivering it is a highly efficient 10.0 percent. How large a solar panel is needed to supply the needs of a 4.7-hp solar-powered car (assuming the car runs directly off the solar panel and not batteries) during a race in Cairo at noon on March 21?

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(c) Assuming a more-realistic efficiency of 4.6 percent and panels capable of rotating to be always perpendicular to the sunlight, how large an array of solar panels is needed to supply the power needs of the International Space Station (ISS)? The ISS requires about 110 kW of continuous electric power.

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