Question

In an experiment to study the scattering of light by passing a beam of white light through a colloidal solution of sulphur in a transparent glass tank:
(a) Which colour is observed from the front of the glass tank? Does this colour correspond to the colour of sky on a clear day or the colour of sky around the sun at sunset?
(b) Which colour is observed from the sides of the glass tank? Does this colour correspond to the colour of sky on a clear day or the colour of sky around the sun at sunset?

Answer 1

a) The colour red of the beam of white light reaches a screen after passing through the colloidal sulphur solution in the transparent glass tank. Therefore, red colour is observed from the front of the glass tank. The colour red corresponds to the colour of the sky around the sun at sunset, because red colour is the least scattered and reaches our eye after the colour blue of white light gets scattered from our line of sight.

b) Blue colour is observed from the sides of the glass tank. The colour blue corresponds to the colour of the sky on a clear day. This is because blue light is scattered easily by the gas molecules of the air in the atmosphere. This scattered light reaches our eyes, which makes the sky appear blue.