Fundamentals of Physics Extended (10th Edition)

$r=+32cm$
Using the relation between focal length and radius of curvature: $$f=\frac{r}{2}$$ Rearranging the equation to make $r$ the subject of the formula:$$r=2f$$ Substituting the known value of $f=+16cm$ yields a radius of curvature of $$r=2(16cm)=+32cm$$