Question

A convex mirror used for rear view on an automobile has a radius of curvature of 3.00m. If a bus is located at 5.00m from this mirror, find magnification?

• A. 0.23
• B. -0.23
• C. 0.45
• D. -0.45

Answer 1

Given,

Radius of curvature = $R=3m$

Focal length = $f=\frac{R}{2}=1.5m$

Object distance = $u=-5m$

Using the mirror formula $\frac{1}{f}=\frac{1}{v}+\frac{1}{u}$ we get

$\frac{1}{1.5}=\frac{1}{-5}+\frac{1}{v}$

$\frac{1}{v}=0.866\Rightarrow v=1.15$ cm

Using magnification $m=-\frac{v}{u}$ we get

$=-\frac{v}{u}=-\frac{1.15}{-5}=0.23$

Thus, the image formed is virtual, erect, and diminished.

Hence, the correct option is A: 0.23.