Question

A convex mirror of focal length 10 cm is placed in water. The refractive index
of water is 4/3. What will be the focal length of the mirror in water

Answer 1

Answer:

focal length of mirror (concave and convex both) does not change when immersed in water as focal length of mirror does not depend on refractive index

Answer 2

Answer:

in water the focal length of given convex mirror will be equal to 15/2cm.

Explanation:

• Refractive index measures the amount of bending in light ray when it travels from one medium to second medium.
• The distance from the lens to focal point is called Focal length . It is positive for convex lens.

Given that the focal length of convex mirror, $f=10cm$

Refractive index of the water, $\mu=\frac{4}{3}$

Then the  ocal length of convex mirror in water  $=\frac{f}{\mu}$ $=\frac{10*3}{4}$

            ∴                      Focal length   $=\frac{30}{4}=\frac{15}{2}cm$              

Therefore in the water convex mirror's focal length is found to be 15/2cm.