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Spectacles with convex lenses correct long-sightedness by…

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BIOLOGY

Spectacles with convex lenses correct long-sightedness by

A. converging the Light rays before they enter the eye

B. diverging the light rays before they enter the eye

C. reducing light intensity before it enters the eye

D. increasing light intensity before it enters the eye

QUICK ANSWER…

A

DETAILS…  

Long-sightedness occurs when the image of an object forms behind the retina; to correct this, the image ray must be made to converge exactly at the retina.

Convex lenses manages to correct long-sightedness by quickly converging the light rays just before they enter the eye so that the image will fall exactly on the retina.

Now to the right option:

  1. Option A is correct; convex lenses are converging lenses used by long-sighted persons to adjust and shorten the distance of image formation in order to correct the defect.
  2. Option B is incorrect; convex lenses do not diverge light rays, concave lenses do. Besides, you do not need to diverge image rays to correct long-sightedness, you need to converge them and bring them nearer.
  3. C is also incorrect; long-sightedness has nothing to do with the intensity of light rays.
  4. D is also incorrect; whether the intensity light is increased or reduced, a long-sighted patient will remain the same.
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QUICK ADVICE…

You may please note that

  • Convex lenses are converging lenses, while convex mirrors are diverging mirrors.
  • Concave lenses are diverging lenses, while concave mirrors are converging mirrors.

You may use the questions and answers session to deal further on this topic…

/culled from 2018 JAMB-UTME biology question 19 /

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