What is long-sightedness (hypermetropia)? List two causes for the development of long-sightedness. Describe with a ray diagram how this defect may be corrected by using spectacles.

(N/A) Long-sightedness,also known as $Hypermetropia$,is a vision defect in which a person can see distant objects clearly but cannot see nearby objects distinctly.
Two causes for the development of $Hypermetropia$ are:
$1$. The focal length of the eye lens is too long.
$2$. The eyeball has become too small.
Correction:
This defect is corrected by using a convex lens of appropriate power. The convex lens converges the light rays coming from a nearby object before they enter the eye,allowing the image to be formed on the retina.
[Ray Diagram Description: $A$ diagram showing the image forming behind the retina in a defective eye,and a second diagram showing a convex lens placed in front of the eye,which converges the rays so that the image is formed exactly on the retina.]