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THE INDISPENSABLE LENS


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.
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