Question

An object is placed at a distance of 25 cm from the spherical mirror, and its image is formed behind the mirror at a distance of 5 cm. Find the focal length of the mirror. Is the mirror concave or convex in nature? Give one use of the mirror so identified.

Answer 1

Dear Student ,
Here in this case applying the equation of spherical mirror we get ,
$$\begin{gathered} \frac{1}{v}+\frac{1}{u}=\frac{1}{f} \\ \Rightarrow -\frac{1}{5}-\frac{1}{25}=\frac{1}{f} \\ \Rightarrow f=-4·16cm \end{gathered}$$
So the mirror is convex mirror and this type of mirror is used as the rear view mirror in cars .
Regards