Question

A student is unable to see clearly the words written on the board placed at a distence of approx 3 m from him. Name the defect of vision the boy is suffering from. State the possible causes of this defect and explain the method of correcting it.

Answer 1

The student is suffering from short-sightedness or myopia.
Causes : a) excessive curvature of the the eye lens
B) elongation of the eyeball

Focal length=-x
So, f=-3
power = 1/f
So power = 1/-3
=-0.33D
Hence a concave lens of power -0.33D can be used for correcting the defect.

Hope it helps ya

Answer 2

Myopia is that defect of vision where one can see nearby objects clearly no but cannot see far away object distinctly.so the defect is myopia.cases for this is 1.excessive curvature of eye lens.2.elongation of eye ball.it can be corrected by using a concave lens of a suitable power.