Question

A dentist wants a small mirror that when placed $2cm$ from a tooth, will produce $3\times$ upright image. What kind of mirror must be used and what must is focal length be?

• A. concave mirror, $3.0cm$
• B. concave mirror, $1.5cm$
• C. convex mirror, $3.0cm$
• D. convex mirror, $1.5cm$

Answer 1

The correct option is A concave mirror, $3.0cm$

for magnification mirror must be a concave mirror

$m=+\frac{v}{u}=\frac{+f}{u-f}$

$3=\frac{+f}{+2+f}\Rightarrow f=3cm$