A concave mirror produces three times enlarged image of an object placed in front of it. Calculate the focal length of the mirror .
Step 1: Given data
(magnification power) =
(object distance) = (taken negatively because it is on the left side )
Step 2: Formulae used
From magnification formula =
From mirror formula
Step 3: Solution
On substituting values in the magnification formula:
From mirror formula
The focal length of the mirror is .