Question

A person wants a ray of light to pass undeviated from a convex lens shown in figure. Where should the incident ray be directed?

• A. C
• B. B
• C. O
• D. A

Answer 1

The correct option is C O

The middle portion of the lens acts as a rectangular glass slab whereas the others acts as prisms. We know that rectangular glass slab refract light in such a way that emergent ray is parallel to the incident ray. Therefore it will emerge on the other side of the lens very slightly displaced, but parallel to the incident one. Since the parallel displacement is too tiny as long as the lens is not too thick, it looks like the ray passes through the center undeviated.