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IB · B · multiple choice

The particulate nature of matter · Question 2

The particulate nature of matter · Original GioPhysics question with a detailed, mark-by-mark answer guide.

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Answer
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multiple choice1 mark

The solar constant is 1360 W m⁻² and the Earth's average albedo is 0.30. What is the average intensity of solar radiation absorbed per square metre of the Earth's surface?

  1. A

    238 W m⁻²

  2. B

    340 W m⁻²

  3. C

    952 W m⁻²

  4. D

    1360 W m⁻²

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Answer overviewCorrect answer: A — 238 W m⁻²
01

Answer and reasoning

1 mark
How to approach it

Predict from the governing principle before looking for a matching option. Then reject alternatives by checking direction, units, limiting behaviour or the physical meaning of each statement.

  1. 1

    The correct choice is A: 238 W m⁻²

  2. 2

    Two steps are needed and each is often missed. B applies the factor of 4 — the ratio of the Earth's surface area to the disc that intercepts the beam — but forgets the albedo. C applies the albedo but forgets the factor of 4.

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