(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

(a) Presbypia is a defect of vision due to which an old person cannot see nearby as well as far off objects clearly due to loss of power of accommodation of the eye.
Causes : presbyopia occurs in old age due to gradual weakening of the ciliary muscles and diminishing flexibility of the eye-lens. The near point of the old person having persbyopia gradually recedes and becomes much thant 25 cm away.
Corrections : Presbyopia defect is corrected by using spectacles having bi-focal lens.
(b) N/A