A biconcave lens made of a transparent material of refractive index is immersed in water of refractive index . Will the lens behave as a converging or a diverging lens? Give reason.
Answer: It behaves as a converging lens.
Solution
Here the surrounding medium is \emph{denser} than the lens material (), so . This reverses the sign of : a biconcave (normally diverging) lens therefore acts as a \emph{converging} lens in water.
CBSE Class 12 Board · 2014 · Delhi · Subjective