- #1

- 45

- 0

## Homework Statement

An object 0.6cm tall is placed 16.5cm to the left of the vertex of a concave spherical mirror having a radius of curvature of 22.0cm.

Determine the position, size, orientation and nature of the image.

## Homework Equations

[itex] \frac {1}{S} + \frac {1}{S'} = \frac {1}{f} = \frac {2}{R} [/itex]

## The Attempt at a Solution

[itex] \frac {1}{16.5}+ \frac {1}{S'} = \frac {2}{-22} [/itex]

[itex] \frac {1}{S'} = -\frac{1}{11} - \frac {1}{16.5} [/itex]

[itex] S' = -6.6cm [/itex]

However, the answer given is 33.0cm, which you get when R = +22.0 , not -22.0

In my lecture notes is definitely says that the radius of curvature for a concave mirror is negative.

Are the notes wrong? Or is there something I am missing?

(Using 33.0cm as S' I can get the answers to the other parts of the question, I just want a little bit of help in understanding why the radius of curvature is positive)

Thanks