physics one more
posted by help? .
A dime .334 m away from, and on the optical axis of, a concave spherical mirror produces an image on the same side of the mirror as the source. The image is .093 m away from the mirror. If the dime is moved on the axis to .229 m from the mirror, how far away from the mirror is the image now?
What is the radius of the sphere of which the mirror is a section?
You don't need the radius of the mirror in this case. Since it and the focal length stay the same,
1/.334 + 1/.093 = 1/.229 + 1/x
Solve for the 'x', which is the new image distance from the mirror.
1/x = 2.994 + 10.753 - 4.367 = 9.38
x = 0.107 m