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InterviewSolution
| 1. |
(a) Focusing Mechanism in the Human Eye |
| Answer» <p>The eye focuses light in a similar way to when you use a magnifying glass to concentrate the Sun’s rays onto a piece of paper. The distance from the magnifyinglensto the piece of paper is thefocal length.</p><p>For the eye, light from distant objects is focused onto theretinaat the back of the eye.</p><p>The eye is about the size of a table tennis ball, so the focal length needs to be about 2.5 cm.</p><p>The cornea does most of the focusing</p><p>The crystalline lens and accommodation</p><p>Behind the aqueous fluid is the second lens system. It consists of a convex lens that is soft and pliable. Theciliary muscleis a circular ring ofmusclethat attaches all the way around the lens. This ciliary muscle can change the shape of the crystalline lens by stretching it at the edges. It is attached to the lens by zonules (ligament fibres that can be tight or loose).</p><p>When you are looking at a near object, the lens needs to become more rounded at the central surface inordertofocusthe light rays. This ability to changefocusfor close-up objects is calledaccommodation.</p> | |