Question

A convex mirror of focal length $f$ (in air) is immersed in a liquid $(\mu =\frac{4}{3})$. The focal length of the mirror in liquid will be:

• A. $\left(\frac{3}{4}\right)f$
• B. $\left(\frac{4}{3}\right)f$
• C. $f$
• D. $\left(\frac{7}{3}\right)f$

Answer 1

The correct option is C $f$

Mirrors, spherical or otherwise are based on the laws of reflection. That behavior is not affected by the medium in which the light travels, so the mirror's focal length would be no different in the air or any other medium.