| Regardless of the source or kind of
light, the ability of light to form an image is dependent upon just one thing--a
small hole or a lens to bring the rays to a focus. The principle of image
formation was discovered in early Greek Times. Later it was realized that the
eye itself has a lens and that an image is, in fact, formed on the retina, the
rear inside surface of the eyeball. Some man inside a cave or a darkened room
noticed that light entering through a small hole in the wall formed an image on
the far wall. It was observed that if you enlarge the hole, the image blurred
and disappeared. On the other hand, the smaller the hole, the sharper the
image-down to a certain diameter after which making the hole smaller makes the
image worse again. The function of a pinhole is to screen out all light rays except those coming in a p A. Modern Lenses B. The Modern Camera C. Lenses and Image Formation D. Development in Photography [简答题]Burning garbage might be one kind of energy source that we can use to help meet our energy needs. (Passage 2)
[简答题]The main light source of the future will almost surely not be a bulb. It might be a table, a wall, or even a fork.
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