1. The problem statement, all variables and given/known data The barrel of a compound microscope is 15 cm in length (distance between lenses). The specimen will be mounted 1.0 cm from the objective, and the eyepiece has a 5.0-cm focal length. Determine the focal length of the objective lens. Known: f2=5cm, L=15cm, do1=1cm Unknown: f1, di1, di2, do2 2. Relevant equations 1/di+1/do=1/f 3. The attempt at a solution A. I drew a diagram: I believe di1+do2=L B. I have the equations: 1/di1+1=f/f1 1/di2+1/do2=1/5 di1+do2=15 I think there is some relation to distances that I'm not seeing.