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A student sitting on the last bench in the class cannot read the writing on the blackboard clearly but he can read the book lying on his desk clearly. Which of the following statement is correct about the student?(a) The near point of his eyes has receded away.(b) The near point of his eyes has come close to him.(c) The far point of his eyes has receded away.(d) The far point of his eyes has come closer to him.
(d) The far point of his eyes has come closer to him.
Explanation
A student sitting on the last bench in the class cannot read the writing on the blackboard clearly but he can read the book lying on his desk clearly. It means he can see nearby objects, but not distant objects, clearly as the far point of the eye is closer to him than normal. He is suffering from a defect called myopia, or near-sightedness.
Myopia, also known as near-sightedness or short-sightedness, is a defect of vision in which a person can't see the distant object clearly (appears blurred), though can see the nearby objects clearly. The far point of a myopic eye is less than infinity.
This defect occurs either due to the high converging power of the eye lens, (because of its short focal length). Or, due to the eye-ball being too long, which causes light to focus in front of the retina, instead of directly on the retina.
It is corrected by using spectacles containing concave lenses, which should be of such a focal length (or power) that it produces a virtual image of the distant object (lying at infinity) at the far point of the myopic eye.
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