How do glasses work?
In: Technology
Glasses as in spectacles??
They are usually concave or convex depending on your problem (myopia or hypermetropia).
Myopic people use concave lenses. The problem with myopia is that the light rays converge before reaching the retina. The image is sharp at the focal point and for a normal person the focal point is at the retina but in myopics the focal point is before the retina. So they have a distorted image.
A Concave lens diverges the incoming light rays a bit before it hits the cornea and lens so that it when it converges it does so at the retina
In the same way in hypermetropic people, the light rays converges at a point beyond the retina.
A convex lens is used in this condition and it helps in converging the light rays further so that it properly focuses at the retina.
There are also other conditions such as astigmatism, where the corneal thickness varies and the image is distorted and wavy, in such conditions a cylindrical lens is used to correct
Hope this helps!!
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