Question

(a) What is hypermetropia?
(b) Write any one cause of hypermetropia.
(c) With the help of a suitable ray diagram, explain how hypermetropia is corrected?

Hint:

Hypermetropia = far-sightedness (near objects blurry). Cause: short eyeball or weak lens. Correction: convex lens (converges rays to focus on retina).

Answer 1

(a) What is Hypermetropia?

Hypermetropia, also known as long-sightedness, is a defect of vision in which a person can see distant objects clearly but cannot see nearby objects distinctly. In this condition, the image of a nearby object is formed behind the retina instead of on the retina.

As a result, close objects appear blurred, while distant objects appear clear.

(b) One Cause of Hypermetropia:

One main cause of hypermetropia is:

– The eyeball is shorter than normal, or
– The eye lens has insufficient converging power (long focal length).

Due to this, light rays from a nearby object do not converge sufficiently and form the image behind the retina.

(c) Correction of Hypermetropia with Ray Diagram:

Hypermetropia is corrected by using a convex (converging) lens.

The convex lens converges the diverging rays coming from a nearby object before they enter the eye. As a result, the image is formed on the retina instead of behind it.

Ray Diagram (Conceptual Representation):

   Near Object        Convex Lens           Eye
        ↑                 ) (               ______
        |                 ) (              /      \
        |                )   (            | Retina |
         \              )     (            \______/
          \            )       (              |
           \__________)_________(______________|

  

Explanation of Diagram:

– Light rays from a nearby object are diverging.
– The convex lens converges these rays before they enter the eye.
– The eye lens then focuses the rays properly on the retina.
– Clear image of the nearby object is formed.

Conclusion:
Hypermetropia is a defect in which near objects are not seen clearly because their image forms behind the retina. It is corrected by using a convex lens, which converges light rays and helps form the image on the retina.