01. (a) What happens to the size of pupil of our eye in
(i) dim light, (ii) bright light ?
(b) Name the cells on the retina sensitive to
(i) Bright light, (ii) dim light.
Q2. A) Why clouds appear white?
b) Why colour of sun appear red during sunrise and sunset?
03. What is atmospheric refraction? What causes atmospheric refraction?
Answers
I can answer your first question answer for your first question first part is our retina expands to get more light to see things in dim light on the other hand in bright light it contracts to prevent damage to retina and to receive less light
The size of the pupil of our eye
(i) becomes large in dim light so as to accommodate more light in the eyes
(ii) becomes small in bright light so that very little light enters the eye
The cells on the retina of the eye that are sensitive to
(i) bright light: cones (cone-shaped cells)
(ii) dim light: rods (rod-shaped cells)
(iii) colour: cones
clouds are white because their water droplets or ice crystals are large enough to scatter the light of the seven wavelengths that combine with each other and produce white light.
Sun appears red at sunrise and sunset because at that time sun is at larger distance from us . Red colours has maximum wavelength and scatters the least so it covers larger distance without scattering while all other 6 colours scatter. That's is why only red colour is seen at sunrise and sunset .
Atmospheric refraction is the shift in apparent direction of a celestial object caused by the refraction of light rays as they pass through Earths atmosphere.
as we move above the surface of the earth density of air goes on decreasing. therefore the light rays suffers multiple refractions before reaching the surface of the earth . this causes atmospheric refraction.