Homework 5/16/00
Q5. When eyes which are able to see distant objects clearly are in the
air, the index of refraction in front of the cornea is 1.00. Since the index of
refraction of the cornea is 1.376, the incoming light rays are bent considerably when
entering the eye as predicted by Snell's Law. The rest of the eye converges the rays
further a real image will be formed on the retina.
When these eyes are underwater, the index of refraction in front
of the cornea is 1.33. This is not too much different than the index of refraction
of the cornea and the incoming light rays are not bent very much. The rest of the
eye is not able to converge the rays enough to form a real image on the retina and forms a
sharp image behind the retina. The image on the retina is therefore blurry.
Q9. Squinting helps to see distant objects because it allows light to come into
the eye through only a small part of the lens. Normally light comes through all of
the lens. Due to the defects in the shape of the lens, each part of the lens focuses
at a different distance. The eye therefore detects a sharp image and many blurred
images on top of one another. By allowing light through only a small part of the
lens, we see the clear image formed by that part of the lens only. The image we see
is not nearly as bright but is more sharply focused.
Q15. Chromatic aberrations occur because of dispersion, the index of refraction
varies with wavelength. Since mirrors work by reflection rather than refraction,
this doesn't make affect image formation.
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