Question

A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard. What advice will a doctor give to her?
A. Doctor advises her to use a convex lens of appropriate power.
B. Doctor advises her to use a concave lens of appropriate power.
C. Doctor advises her to use a plane mirror of appropriate power.
D. Doctor advises her to use a plane convex lens of appropriate power.

Answer 1

The two very common types of the vision conditions are nearsightedness and farsightedness. These are abnormalities of the eye or the refractive errors which affect its ability to focus light on the retina. To correct the vision defect different types of lenses are used.

Complete step by step answer:
A student sitting at the back of the classroom cannot read clearly the letters written on the blackboard, as she is suffering from near-sightedness or myopia. A person suffering from the myopia can see nearby objects clearly but cannot see distant objects distinctly. A person suffering from this defect has the far point nearer than infinity. That person may see clearly up to a distance of a few meters only. This defect can be corrected by using the concave lens of appropriate power.

As shown in the above figure, in a myopic eye, an image of the distant object is formed in front of eye

and not on the retina.

As shown in the above figure, for the correction of Myopia, the concave lens is placed in the front of the eye lens forms a virtual image of the distant object at far point (F) of the myopic eye.Doctor advises a student to use a concave lens of appropriate power.

Hence, from the given multiple choices – the option B is the correct answer.

Note:
Please understand the difference between the far sightedness (hyperopia) and the near sightedness (myopia) and the types of lenses used to correct the vision defect. To correct hyperopia defects can see far objects and cannot see near objects clearly. To correct these vision defects, the convex lens is used.