Question

A student has difficulty in reading the blackboard while sitting in the last row. From the given options, choose the defect child is suffering from and its correction measures:
(A) Defect: Myopia
Correction: Concave lens of suitable focal lens
(B) Defect: Hypermetropia
Correction: Convex lens of suitable focal length
(C) Defect: Myopia
Correction: Medicines
(D) Defect: Hypermetropia
Correction: Medicines

Answer 1

Hint : In order to find the correct answer to this question, we will be looking at the different kinds of defects a human eye can have and what can be done to outcome those defects. We will use the situation given in the question and find the type of defect the student is facing, then find the best way of correcting such a defect.

Complete Step By Step Answer:
As we know that the objects are visible only because of the light getting reflected from the object and this reflected light enters our eyes and we see the object.
We know that there is a convex lens inside an eye which is controlled by the ciliary muscle and helps to converge the reflected light coming from the object to form an image. For a person who is having an eye defect, the ciliary muscles do not work properly and hence, the rays are not focused on the retina and the image is blurred.
Based on this, we can differentiate the defects into three types:
Myopia (nearsightedness): In this kind of defect, the rays coming from far away objects are focused before the retina and hence the image appears blurry whereas the nearby objects are seen clearly. This type of defect can be corrected by using a concave lens.
Hypermetropia (farsightedness) : In this kind of defect, the rays coming from the nearby objects form an image behind the retina and hence resulting into a blurred image. Whereas the far away objects can be seen clearly. This type of defect can be corrected using convex lenses.
Astigmatism: This kind of defect occurs when all the light rays are not focused at the retina but instead, some of them are focused behind the retina whereas some are focused before the retina. It is mainly caused due to non-uniform formation of cornea and is from birth. This kind of defect can be corrected through a special kind of lens.
Now looking at all that we have studied and recalled, we can say that the child suffering from the eye defect in the question is suffering from Myopia (as he is not able to read the blackboard from sitting on the last bench) and the only correction is using a concave lens of suitable focal lens.
Therefore, option (A) is the correct answer.

Note :
The distance of the blackboard from the boy sitting on the last bench is quite large. There are many other factors which affect the vision of eyes out of which the upper three are the most common and easily corrected without surgery.