# A couple of optics questions

#### jlmac2001

1. Imagine that you are standing 5 ft from and looking directly toward, a brass ball 1 foot in diameterhanging in front of a pawn shop. Describe the image you would see in the ball.

-Would I have to find the an answer that tells me that it is inverted, real, virtual, etc?

2. What formula would I useto find the radius of curvature? if the magnification of a keratometer is found to be 0.037X when the object distance is se at 100 mm, what is the radius of curvature?

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#### dduardo

Staff Emeritus
Mirror problems are a little difficult to do in a forum. It really helps to have a picture. I highly suggest you do a google search on convex mirrors and look at the examples done in your physics book. For this types of problems DRAW A PICTURE and make sure you label everything

The equation you would use is
1/s' + 1/s = 1/f where 1/f = 2/R

R is the radius of curvature
f is the focus
s is the distance from your eye to the front of the mirror
s' is the distance from the front of the mirror to the image (may it be real or virtual)

m = -s'/s where m is the magnification

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