State one role of ciliary muscles in the human eye?
Ciliary muscles holds the eye in its place. Also, it changes the shape of the lens by contracting or relaxing the muscles. This process is known as accommodation.
What is the colour of the sky during day time? Give reason for it?
The colour of the clear sky is blue during the day time. This is because of the scattering of light by the atmosphere. The spectrum of white light comprises of different colours. Out of these colours, the blue colour gets scattered the most because of its shorter wavelength as compared to the long wavelength of red colour.
What is meant by scattering of light? Use this phenomenon to explain why the clear sky appears blue or the Sun appears reddish at sunrise?
Scattering of light is the phenomenon in which a part of the incident light is dispersed in different directions.
A narrow beam PQ of white light is passing through a glass prism ABC as shown in the diagram.
Trace it on your answer sheet and show the path of the emergent beam as observed on the screen DE.
(i) Write the name and cause of the phenomenon observed.
(ii) Where else in nature is this phenomenon observed.
(iii) Based on this observation, state the conclusion which can be drawn about the constituents of white light.
Draw a labelled ray diagram to illustrate the dispersion of a narrow beam of white light when it passes through a glass prism.