Question

A dentist’s concave mirror has a radius of curvature of 30cm. How far must
it be placed from a cavity in order to give a virtual image magnified five
times?

Answer 1

Answer:

from mirror formula 1/u+1/v=1/f ,f=r/2 then m =v/u ,m =5, v/u=5,v=5u put in mirror formula 1/u+1/5u=1/15,u=-18,v=5u,v=18*5=90 cm