(a) What is presbyopia ? State its cause. How is it corrected ?
(b) why does the sun appear reddish early in the morning ? Explain with the help of a labelled diagram.

Explanation

Presbyopia is the defect of vision in which aged people find it difficut to see nearby objects comfortably and clearly without spectables.
Reason of presbyopia : The power of accommodation of eye usually decreases with ageing . The muscles near the eye lens lose their ability to change the focal length of the lens. Therefore, the near point of the eye lens shifts farther from the eye.
This defect is correct using a convex lens of appropriate power. The lens converges light rays before they fall on the eye lens such that the action of the eye lens forms the image on the retina.