Question

A person uses lenses of power -0.5 D in his spectacles for the correction of his vision. (a) Name the defect of vision the person is suffering from.

Hint:

Myopia (nearsightedness) is corrected using concave lenses, which diverge light rays to focus images on the retina.

Answer 1

Step 1: Understanding Lens Power

• The power of the lens used is -0.5 D (diopters).
• The negative sign indicates that the lens is concave (diverging lens).

Step 2: Which Defect Does a Concave Lens Correct?

• Concave lenses are prescribed for people who have myopia (also known as short-sightedness).
• In myopia, a person can see nearby objects clearly but distant objects appear blurred.

Step 3: Final Answer

The person is suffering from myopia (short-sightedness). This is why he uses a concave lens with negative power for vision correction.