Given below is a diagram depicting a defect of the human eye. Study the same and then answer the questions that follow: Given below is a diagram depicting a defect of the human eye. Study the same and then answer the questions that follow:
With the help of a diagram show how the defect shown above is rectified using a suitable lens.
Topic: Correction of myopia — diagram
Answer
Draw a ray diagram of the eye with a CONCAVE LENS placed in front of it, showing: • parallel rays arriving from a distant object • the CONCAVE LENS (thin in the middle, thick at the edges) DIVERGING them slightly • the diverged rays then entering the eye and being converged by the cornea and lens • the rays now meeting EXACTLY ON THE RETINA, forming a sharp image
Labels required: concave lens, cornea, eye lens, retina, image formed on the retina.
THE POINT THE DIAGRAM MUST MAKE is that the focus has MOVED BACK onto the retina. Draw the uncorrected case beside it if you have room — rays meeting in front of the retina — so the contrast is visible.
GET THE LENS SHAPE RIGHT: a concave lens must be drawn THIN IN THE MIDDLE and THICKER AT THE EDGES, with the rays visibly SPREADING as they pass through. A lens drawn the wrong way round contradicts your own answer to part (iii).
Use a ruler for the rays and arrowheads to show the direction of travel. Neat straight lines are part of what the mark is for.