Skip to content

The colour of clear sky from… (Class 10 Science 2023, Q25B)

questionbuddy.in/q/cbse-10-science-2023-31-4-1-q25b-colour-clear-sky-earth-appears

ScienceCBSE Class 10 · Board exam 2023, set 31/4/1 · 2 marks · Very short answer

CBSE Class 10 Science 2023: question 25(B)

Set in the CBSE Class 10 board exam of 2023, paper 31/4/1, section B, question 25(B), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q25(B) · 2 marks · Very short answerThe Human Eye and the Colourful World

The colour of clear sky from the earth appears blue but from the space it appears black. Why ?

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 31/4/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

The phenomenon involved is scattering of light.

Hint 2

Compare the particle size with the wavelength. Which colour is scattered most by very small particles?

Hint 3

What is missing in space that is present around the earth?

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. The molecules of air and fine particles in the atmosphere are smaller than the wavelength of visible light. They scatter shorter wavelengths (blue) much more than longer ones (red). This scattered blue light enters our eyes, so the sky looks blue from the earth.

    1 mark

  2. In space there is no atmosphere, so there are no particles to scatter sunlight. No scattered light reaches the eye, so the sky appears black (dark).

    1 mark

Answer: Blue from earth due to scattering of blue light by fine atmospheric particles; black from space since there is no atmosphere to scatter light.

Where the marks are

  • Fine particles smaller than the wavelength scatter blue light more (1 mark)
  • No atmosphere in space, so no scattering and the sky looks dark (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from The Human Eye and the Colourful World, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 31/4/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.