Lenses and the Human Eye

Lenses and the Human Eye - Lenses and the Human Eye James...

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Lenses and the Human Eye James Pou, Warren College, UCSD Phys 2CL T/Th 5-8 Aug 28 th , 2009 Abstract: The objective of the lab was to study the behavior of focusing and spreading light in a lens. Focal wave length was measured using a light source, optical bench, convex lens, concave lens, lens holder, ruler, and a screen. The expected value for the combination of focal lengths of L1 and L2 came out to be 7.5 +/-0.1 cm. The accommodating power of my eye was about 12.57 diopters which is equal to that of an 16-20 year old. My blindspot was found to reside 0.51+/- 0.02 cm below my fovea. Introduction: The purpose of the experiment is to understand the function and application of lenses in our daily life, including those in our eyes. Learning to understand the functions of focusing and spreading light of simple lenses can be beneficial to our knowledge of more complicated equipments with lenses like telescopes or microscopes, and even glasses. In experiment 7, convergent and concave lenses were used to find the focal lengths and power of various lenses. The relations of the distance from the lens (u) and the distance from the lens to screen (v) were analyzed with uncertainties on an ORIGIN fit graph. Maximum focal length of an eye was found by using the measured far point and plugging it into the lens formula. The near point (u near ) was measured to find the f min and the P max respectively. The f max value was used in determining the P min and the accommodating power of the eye in diopters. P max and P min were then used to find P acc, the accommodating power of my eye. In the last part, we determined our projected blindspot using a whiteboard and laser,
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then used measurements in addition to the magnification factor of our eyes to determine the dimensions and location of the real source of the blindspot , a cluster of optic nerves residing on the retina. Theory: In the first part, focal lengths f 1 and f 2 were found from the measurement of v (the distance from screen to lens). A lens’ focal length was calculated by combining the focal lengths of the respective lenses with the lens addition formula. The lens addition formula is: = + 1f 1f1 1f2 The power of a lens is defined by the deflection of its incident rays, which varies inversely (higher power constitutes shorter focal length). The power of a lens is defined by P = 1 / [f(m)], units = diopters. Thus the lens addition formula in terms of power is P = P 1 + P 2 . The lens formula was used and its data was graphed 1/u vs 1/v to produce the magnification.
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This note was uploaded on 10/22/2009 for the course CHEM 140A taught by Professor Whiteshell during the Spring '04 term at UCSD.

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Lenses and the Human Eye - Lenses and the Human Eye James...

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