Scattering of Light (Tyndall Effect, Blue Sky, Red Sun) MCQs

Q1. What is the effect of the size of the scattering particles on the colour of the scattered light?

• A.The size of the scattering particles has no effect on the colour of the scattered light.
• B.Very fine particles scatter mainly red light while particles of larger size scatter light of shorter wavelengths.
• C.Very fine particles scatter mainly blue light while particles of larger size scatter light of longer wavelengths.
• D.The size of the scattering particles has a random effect on the colour of the scattered light.

Answer: C. Very fine particles scatter mainly blue light while particles of larger size scatter light of longer wavelengths.

Q2. In a smoke-filled room, a beam of sunlight entering through a small hole becomes visible. Which phenomenon is responsible for making the path of the beam visible?

• A.Scattering of light (the Tyndall effect)
• B.Total internal reflection of light
• C.Dispersion of light
• D.Refraction of light

Answer: A. Scattering of light (the Tyndall effect)

Q3. Consider the following statements about scattering of light: (I) The Tyndall effect is scattering by colloidal particles. (II) The sky looks black to an astronaut in space. (III) Red light is scattered more than blue. Which of the above statement(s) is/are correct?

• A.Only I
• B.None of these
• C.Only III
• D.Only I and II

Answer: D. Only I and II

Eliminate first - option A) 'Only I' doesn't hold - Re-check each statement individually; option B) 'None of these' fails since Re-check each statement individually; option C) 'Only III' misses the point - Re-check each statement individually. That leaves only option D). Confirm with the chapter rule: Correct: I, II (physics, chapter 'The Human Eye and the Colourful World'). Answer: D) Only I and II.