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water drop lens |
Lens is everywhere. It
is found in telescope, microscope, camera, projector, binoculars and spectacles
and so on. The lens rules the world even
today.
Eye lens is
natural one. At one moment, we can see
ant moving on the floor. The next moment
we can see the stars in the sky. Eye lens
can change shape automatically and there by alter its focus according to the distance
of the object. That is a natural
wonder. We still struggle to duplicate
it.
Eye lens loses
its transparency and become opaque due to aging. That is cataract. In cataract surgery, the natural lens is
replaced by artificial one. Cataract
surgery is one of the highest numbers of surgeries done worldwide.
How to see without spectacles?
You need not
worry, if you miss the specs. A pinhole
in a camera box (light tight box) acts as the lens and forms the image on the
opposite side as shown in figure. A
pinhole can focus the object at any distance.
So take a thick card and make a pinhole.
You can clearly see the object through the hole without glasses.
The refraction and the shape of the glass are responsible for the lens effect-focusing. The lens always forms inverted image and the
brain erects it.
More info:
1. 1. Water drop is spherical so it acts as a lens as
shown in figure.
2. 2. Like glass lens we have electromagnetic lens to focus
electron beam(electron microscope).
3. 3. In a theater, we sit between the lens and the
screen. That distance plays the crucial
role in magnification of the image.
4. 4.There is a substitute for glass lens called
Fresnel lens (a flat one) which is not so effective
Long
live the lens.