Question

A $1.2cm$ long pin is placed perpendicular to the principal axis of a convex mirror of focal length $12cm$, at a distance of $8cm$ from it. Is the image erect or inverted?

Answer 1

Distance of object from mirror $u=-8cm$

Focal length $f=12cm$

We know for mirror,

$\frac{1}{f}=\frac{1}{v}+\frac{1}{u}$

$\frac{1}{12}=\frac{1}{v}+\frac{1}{-8}$

Distance of image from lens $v=4.8cm$

Magnification ratio $m=-\frac{v}{u}=-\frac{4.8}{-8}=0.6$

Since magnification ratio is positive, thus image is erect .