PHYS 284 Lecture Notes - Lecture 6: Distant Star, Retina, Gamma Ray
5 Apr 2018
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The eye is a remarkably complex organ, but its basic components are a pupil, a lens,* and a retina. The pupil controls how much light enters the eye; it dilates (opens wider) in low light and constricts in bright light. The lens bends light to form an image on the retina. The retina contains light-sensitive cells (called cones and rods) that, when triggered by light, send signals to the brain via the optic nerve. The lens of the eye creates an image by bending light in much the same way as a simple glass lens. You can understand why light bends by imagining a light wave coming toward you from far away. The peaks a(cid:374)d t(cid:396)oughs of the ele(cid:272)t(cid:396)i(cid:272) a(cid:374)d (cid:373)ag(cid:374)eti(cid:272) fields a(cid:396)e pe(cid:396)pe(cid:374)di(cid:272)ula(cid:396) to the light (cid:449)a(cid:448)e"s di(cid:396)e(cid:272)tio(cid:374) of t(cid:396)a(cid:448)el. The wave slows down when it hits glass or your eye because light travels more slowly through denser matter than through air.
