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Unformatted text preview: Physics 208, Spring 08, Week 12 Quizzes 1. Multiple choice 1. The Earth is about 1.49 x 10 8 km from the Sun. If the solar radiation at the top of the Earth’s atmosphere has an intensity of 1340 W/m 2 , what is the total power output of the Sun? a. 7.10 x 10 27 W b. 2.20 x 10 30 W c. 6.62 x 10 26 W d. 3.74 x 10 26 W [Hint: assume isotropic radiation emission from the Sun in order to calculate the area of a sphere at a distance equal to the Earth-Sun distance.] Solution d) I = P/A Assuming isotropical emission A = 4 π R 2 P = IA, with R distance Earth – Sun. 2. If the radiant energy from the Sun comes in as a plane EM wave of intensity 1340 W/m 2 , calculate the peak values of E and B. a. 300 V/m, 10-4 T b. 1005 V/m, 3.35 x 10-6 T c. 225 V/m, 1.6 x 10-3 T d. 111 V/m, 3 x 10-5 T Remember that ε = 8.85 x 10-12 C 2 / (N m 2 ). You can then derive μ if you do not remember it… Solution: b E max = 1005 V/m B max = 3.35e-6 T 3. Find the force exerted by reflecting sunlight off a perfectly reflecting 3....
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