Q4E - University Physics with Modern Physics

Question

A concave mirror has a radius of curvature of 34.0cm. (a) What is its focal length? (b) If the mirror is immersed in water (refractive index 1.33), what is its focal length?

Step-by-Step Solution

Answer

1. $f=17cm$
   
2. $f=17cm$
   

Step 1: Calculate the focal length using the radius of curvature

The radius of curvature of concave mirror is always positive, therefore, the same is for the focal length. The radius is twice of the focal length.

$$\begin{gathered} f=\frac{R}{2} \\ f=\frac{34}{2} \\ f=17cm \end{gathered}$$

Step 2: Focal length in case of water

The focal length is independent of the medium in which it is immersed. So, the focal length will stay same in water, that is, $f=17cm$.