(a) A student cannot see clearly a chart hanging on a wall placed at a distance of 3 from his eyes. Name the defect of vision he is suffering from. Draw a ray diagram to illustrate this effect . List its two possible causes.; (b) Draw a ray diagram to show how this defect maybe corrected using a lens appropriate focal length.; (c) An eye donation camp is being organized by social workers in your locality. and why would you help in this cause?(All India - 2013)
Answers
Answer:
This is the answer .
A student cannot see clearly a chart hanging on a wall placed at a distance of 3 from his eyes- Due to Hypermetropia
Explanation:
Hypermetropia
It is also called as farsightedness
Is a defect in which person is unable to see near objects but can see for off objects clearly.
Cause
Accommodation problem
It is due to some reasons cilliary muscles do not contract properly, lens do not become thick and short due to which focal length doesn’t decrease. As a result image formed is not clear and can’t be identified by brain.
Eye defect
The eye ball being too short
The converging power of lens being too low
Due to which image is formed behind the retina as shown below
Correction
It is done by using spectacles containing convex lens that increase the c. power of eye lens so, that it can converge rays properly on retina as shown below .
An eye donation camp is being organized by social workers in your locality in which we would like to test the eye sights of different persons , prescribing about the numbers of spectacles and will talk about the diet they should eat for healthy lifestyle and healthy body .