Q1.
Where all are the lenses used?
Answer
Lenses are used almost everywhere we need to control where light goes.
| Where | What the lens does there |
|---|---|
| Eyeglasses (spectacles) | Bend the light a little before it enters the eye, so that a clear image is formed for the wearer |
| Cameras, including smartphone cameras | Converge light from the scene to form a sharp image on the sensor |
| Telescopes | Gather light from distant objects in the sky |
| Microscopes | Give a greatly enlarged view of very small objects |
| Magnifying glass | Makes small print appear bigger |
| Inside our own eye | A convex lens that can change its shape, letting us look at a book and then at something far away |
Why the eye lens is the most remarkable of them all: every lens in the list above has one fixed curvature, so it converges light by one fixed amount. The lens in our eye can change its shape — becoming more curved for near objects and flatter for distant ones — so a single lens does the work of a whole set. That is how we read a line of print and then look up at a hill without changing anything.