In: Physics
A) The medium-power objective lens in a laboratory microscope has a focal length fobjective = 4.00 mm . If this lens produces a lateral magnification of -37.0, what is its "working distance"; that is, what is the distance from the object to the objective lens B) What is the focal length of an eyepiece lens that will provide an overall magnification of -115? Assume student's near-point distance is N = 25 cm.
PART A For the objective lens,
Lateral Magnification is -37.0
, where u is distance of object and v is distance of image from the objective lens.
Equation of lens is
Here,
, taking into account the sign conventions for u and real image formed at v.
The working distance of the microscope is 4.11 mm.
PART B :
Overall magnification M is given by
Here,
Since the image is to be formed at the near point of the student's eye, which is 25 cm,
Focal length of eyepiece lens is 8 cm.