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Lecture 29

# Lecture 29 - Recap of last lecture Human eye most of the...

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Recap of last lecture Human eye: most of the bending (refraction) due to the cornea which has a small focal length. The lens is used to get additional variable focusing so that near and far objects can be on focus at the retina Normal eye near point = 25 cm. far point = infinity Nearsighted eye (myopic) : eyeball too big, distant objects focus in front of the retina, can be corrected with a diverging lens Farsighted eye (hyperopic): eyeballs too small, nearby objects focus behind the retina, can be corrected with a converging lens. Power of a lens is given by P = 1/f in diopter (inverse m). Astigmatism is caused by the cornea not being completely spherical, which causes the focus along the one direction (eg. horizontal) to be different from some other direction (eg. vertical). Can be corrected using cylindrical lenses

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Problem 34.85 The cornea of the eye has a radius of curvature of approx. 0.5cm, and the aqueous humor behind it has an index of refraction of 1.35. The thickness of the cornea itself is small enough that we can neglect it. The depth of a typical human eye is around 25 mm. a) What would have to be the radius of curvature of the cornea so that it alone would focus the image of a distant mountain on the retina, which is at the back of the eye opposite the cornea?
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Lecture 29 - Recap of last lecture Human eye most of the...

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