1. Solar Radiation Goals: Understand solar radiation and solar constant; qualitative effects of incident angle.

2. Q1 A detector is measuring solar radiation intensity I at point A, B, C. Which is true? 1)I(A) > I(B) > I(C); 2)I(A) > I(C) > I(B); 3)I(C) > I(B) > I(A); 4) I(B) > I(A) > I(C).

3. Q2 You see someone plotted the radiation intensity as a function of distance from the sun, R. Which one is true? A) I(R) increases as a function of R; B) I(R) decreases as a function of R; C) I(R) is independent of R;

4. Solar radiation constant Solar radiation intensity near the earth is called solar radiation constant. It is about S=1367W/m^2. Why not higher or lower?

5. Q3 On a planet that is at distance d=5 a.u. from the sun, the solar constant is about A) 54 W /m^2; B) 270 W /m^2; C) 1,367 W /m^2; D) 5W / m^2.

6. Power per unit area versus the distance http://hyperphysics.phy-astr.gsu.edu/hbase/forces/isq.html

7. Q4 A solar-battery powered heater is used to heat water in a house. The surface area of the solar panel is 5m^2 and efficiency is 25%. At noon time under direct sunshine, what is the output power of the solar battery? A) 5W; B) 75 W; C) 1.75 kW; D) 10kW.

8. Q5 During the noon time, to power a heater which works with input power 5kW, the surface area of the solar panel should be around A) 1m^2; B) 8m^2; C) 15m^2; D) 30m^2.

9. Incident-angle (theta) dependence of intensity. theta A’A >

10. Energy per square meter decreases at lower sun angles and shorter daylight periods.