[单选题]
A compound microscope has a 18-cm barrel and an objective with arls()pr (jd*2 0m ahol, .orxk focal lengthspj(l(. 9vwwomae,- i of 8.0 mm. What is the focal length of ae9i,.pol j -w(vsm(wthe eyepiece to give a total magnification of 240?
A. $0.13 \; cm$
B. $1.5 \; cm$
C. $1.9 \; cm$
D. $2.3 \; cm$
Post time 2024-1-26 22:03:25