Question

What is the radius of curvature of a convex mirror if the focal length is $60\text{cm}$?

• A. $+120\text{cm}$
• B. $-120\text{cm}$
• C. $40\text{cm}$
• D. $60\text{cm}$

Answer 1

The correct option is A $+120\text{cm}$


We know that
Focal length of the mirror, $f$ = Half of radius of curvature, $\frac{R}{2}$
$f=\frac{R}{2}$
$\Rightarrow R=2f=2\times \left(60\text{cm}\right)=120\text{cm}$
$R=+120\text{cm}$