Question

Radiusof curvature of concave mirror is 40cm object placed on 40cm what is focal length and image distance​

Answer 1

Refere to the Attachment ✌️

Answer 2

Solution :

Given:

The radius of curvature of a concave mirror is 40 cm and an object is placed on 40 cm.

We know that:

$\implies$ $\boxed{\sf{\frac{1}{f} = \frac{1}{v} + \frac{1}{u}}}$

Here:

R = 2f, ∴ f = 20

By substituting the values:

$\implies$ $\sf{-\frac{1}{20} = \frac{1}{v} - \frac{1}{40}}$

$\implies$ $\sf{\frac{1}{v} = -\frac{1}{20} + \frac{1}{40}}$

$\implies$ $\sf{\frac{1}{v} = \frac{- 40+20}{20\times40}}$

$\implies$ $\sf{\frac{1}{v} = - \frac{20}{800}}$

$\implies$ $\sf{\frac{1}{v} = -\frac{1}{40}}$

$\implies$ $\sf{v = - 40\:cm}$

Therefore:

The focal length is 20 cm and the image distance is - 40 cm.