IB Physics SL B.2.3 Albedo

Practise calculating albedo from reflected and incident power, separating reflected from absorbed fractions and inserting the result into regional or planetary energy balances.

Syllabus
First assessment 2025
Objective
—
Level
SL

Exam points

  • calculate albedo as reflected power divided by incident power over the same boundary
  • find absorbed intensity with (1 - α)I and avoid treating albedo itself as the absorbed fraction
  • combine albedo with S/4 or a local incident intensity in an equilibrium calculation

B.2.3—Albedo question 1

[Maximum number: 1]

The Moon has no atmosphere and orbits the Earth. The diagram shows the Moon with rays of light from the Sun that are incident at 90∘90^{\circ} to the axis of rotation of the Moon.

Figure for Question B.2.3—Albedo question 1 — IB Physics SL

The albedo of the Earth's atmosphere is 0.28 . Outline why the maximum temperature of a black body on the Earth when the Sun is overhead is less than that at point A on the Moon.

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