Question

A lens having two spherical surfaces, curved inwards, is called

• A. concavo-convex
• B. plano-convex
• C. biconvex
• D. biconcave

Answer 1

The Correct Option is D

A lens that has both of its spherical surfaces curved inward (concave) is called a biconcave lens.  
Such lenses are thinner at the center than at the edges and diverge light rays passing through them.  

- If one side is flat and the other is concave, it's called plano-concave.  
- If both sides are convex, it's biconvex (used to converge rays).  
- If one side is convex and the other concave, it’s concavo-convex.  
- But if both sides are concave (curving inward), the correct name is biconcave.
 

The correct option is (D): biconcave