(a) Write the function of each of the following parts of human eye: (i) Cornea (ii) Iris (iii) Crystalline…
(a) Write the function of each of the following parts of human eye:
(i) Cornea (ii) Iris
(iii) Crystalline lens (iv) Ciliary muscles
(b) Why does the sun appear reddish early in the morning? Will this phenomenon be observed by an astronaut on the Moon? Give reason to justify your answer.
Solution
(a) Function of Human eye:
(i) Cornea focuses light ray to enter the eye.
(ii) Iris control and regulate amount of light entering the eye and control the size of pupil.
(iii) Crystalline lens is like a convex lens which converge light rays on the retina.
(iv) Ciliary muscles adjust focal length of eye lens by contraction and relaxation so that sharp image can be obtained on the retina.
(b) During morning and evening time, sun is at the horizon, sunlight has to travel longer distance in atmosphere. Violet and blue colours etc. of shorter wavelength scatter in the space only. The longer wavelength red colour reaches to the observer on earth and sun appears reddish. No, because there is no atmosphere on moon and no scattering of light takes place there.