Question

Why do we use lenses of very thin aperture?

• A. So that we do not waste too much glass
• B. So that the ray passing through optical centre goes un-deviated
• C. Thin lens has large focus
• D. All of these

Answer 1

The correct option is B

So that the ray passing through optical centre goes un-deviated

As it is evident from the figure, the greater the thickness of the glass slab, the more is the deviation. Tthe centre of the lens is similar to a glass slab. So, we make the lenses thin so that the light ray goes undeviated if it falls on the pole.