Question 1

Multiple choiceEasy1 mark

A region of Earth is measured twice. Its albedo is unchanged between measurements; the incident and scattered powers are shown. Which row gives the albedo and the scattered power in the later measurement, respectively?

MeasurementIncident power / WScattered power / W
First600150
Later1200—
Show answer and explanation

Answer: D. Albedo is total scattered power divided by total incident power. The first measurement gives 150/600=0.25150/600=0.25 With albedo unchanged, the later scattered power is 0.25×1200 W=300 W0.25\times1200\text{ W}=300\text{ W}
A: Keeps the initial scattered power instead of scaling it for the increased incident power.
B: Adds scattered power to incident power in the denominator, giving an albedo of 150/(600+150)=0.20150/(600+150)=0.20
C: Uses the non-scattered fraction, 1−0.25=0.751-0.25=0.75 as the albedo.
Remember: multiply incident power by albedo to find scattered power.

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