Question

A concave mirror having a radius of curvature 40 cm is placed in front of an illuminated point source at a distance of 30 cm from it.Find the location of the image.
I got 6cm as my answer and its wrong

Answer 1

C at 40
F at 20

object at 30, halfway between C and F
so
image is BEYOND C

http://www.physicsclassroom.com/class/refln/Lesson-3/Image-Characteristics-for-Concave-Mirrors

Answer 2

1/f = 1/do + 1/di

1/20 = 1/30 + 1/di

60/20 = 60/30 + 60/di

3 = 2 + 60/di

di = 60 cm