Question

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

• A. $f$
• B. $\frac{f}{3}$
• C. $\frac{3}{4}f$
• D. $\frac{7}{3}f$

Answer 1

The correct option is A $f$

On immersing a mirror in water, focal length of the mirror remains unchanged because focal length of the mirror depends on the geometry and radius of curvature which is unchanged.