Question

What is short-sightedness ? State the two causes of short-sightedness (or myopia). With the help of ray diagrams, show 

 1. the eye-defect short-sightedness.

2. correction of short-sightedness by using a lens.

Answer 1

Short Sightedness is that defect of vision due to which a person can see nearby objects clearly but cannot see distant objects clearly.

Causes: 

1. Excessive curvature of the eye lens

2. Elongation of the eyeball Ray diagram for: 

(i) eye-defect short sightedness

The far point(F) of a myopic eye is less than infinity

(ii) Correction of short-sightedness by using a lens

Correction of myopia. The concave lens placed lens placed in front of the eye forms a virtual image of distant object at far point (F) of the myopic eye