Question

an object is 6cm from the wall using a concave mirror to project an image of that object. the image is 3times the size of the object. how far should the mirror be from the wall? what should its radius of curvature be?

Answer 1

$$m=3=-\frac{v}{u} =-\frac{-(6+u)}{u} \\u=3\ cm$$

$$d=6+2u=12\ cm$$

$$\frac{2}{R}=\frac{1}{-9}+\frac{1}{3}\\R=9\ cm$$