- #1
genevievelily
- 16
- 0
Homework Statement
In the photo (which I cannot post now, but it is a magnifying glass, and a dollar bill) the images through the lens appears twice the size and it is at a distance of 3.0cm from the lens of the magnifying glass. Determine focal length.
Homework Equations
1. -di/do=m
2. 1/f=1/di+1/do
The Attempt at a Solution
Since twice the size m will be 2. Using equation 1:
di=-m*do
= -2*3.00cm
= -6.00cm
This makes sense since image is upright and virtual, and in lenses virtual images are negative.
When I calculate focal length,
1/f=1/-6+1/3
f=6
But this answer is wrong the answer is 3. What am I doing wrong or what do I not understand?
Thanks!