a) What is hypermetropia? What are the two causes of theis defect of vision.
b) What is the colour of the clear sky during day time. Give reason for it.

Explanation

a) Hypermetropia is the defect in which a person can see distance objects clearly but cannot see the nearby objects.
The two possible causes of this defect are :
* Increase in the focal length of the eye lens,
* Eyeball gets shortened.
b) When sunlight passes through the atmosphere having the molecules of air and other fine particles whose size is smaller than the wave length of visible light these molecules and particles scatter the blue colour more strongly than the other colours of spectrum as the wave length of blue colour is more. This scattered blue light enters our eye, so the colour of sky apepars blue to us during day time.