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(a) What is presbyopia ? State its cause. How is it corrected?(b) Why does the Sun appear reddish early in the morning ? Explain with the helpof a labelled diagram. |
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Answer» a. Long-sightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age. Most experts believepresbyopiaiscausedby changestothe lens inside the eye. As people age, the lens becomes harderandless elastic, making it more difficult for the eyetofocus on close objects. For centuriespresbyopiawascorrectedwith the use of bifocal eyeglasses. b. Light from theSunnear the horizon passes through a thicker layer of air and a larger distance in the Earth's atmosphere before reaching our eyes. However, near the horizon, most of the blue light and shorter wavelengths are scattered. |
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