Question

a concave mirror with a focal length if 16.0 cm produces an image located 38.6 cm from the mirror. What is the distance of the object from the front of the mirror?

A) 34 cm
B) 3.5 cm
C) 14 cm
D) 19 cm

I don't know the formula to solve this..

Answer 1

I believe you can use the thin lense equation to solve this problem... but, from what I understand, you'd need the focal length to determine the exact distance.

Answer 2

actually, yeah - just re-read your question... you have the focal length, so if you know what side of the mirror your focus is on, you should be able to properly calculate the distance with the thin lense equation:

\[\frac{ 1 }{ f }=\frac{ 1 }{ d_o }+\frac{1}{d_i}\]

Answer 3

why give a cookie cutter equation that does not directly solve for f?
reciprocal, hello? if you want to give an equation that solves for f, then make that equation solve for f :P

\[\frac{1}{f} = \frac{d_1+d_0}{d_0d_1} \rightarrow f = \frac{d_0d_1}{d_1+d_0}\]