A compound microscope has an objective with a focal length of 3.00 mm and an eyepiece of focal length 6.00 cm.It is adjusted for minimum eyestrain for persons with a near point of 25 cm.If the two lenses are separated by 40.0 cm,what is the total overall magnification?
A)28
B)56
C)470
D)550
E)2200

Question

Quizplus · Accepted Answer

Total magnification of a compound microscope is given by the product of the magnification of the objective lens and the magnification of the eyepiece.

Magnification of the objective lens,
M1 = −fo/fe = −3.00 mm/6.00 cm = −0.5

Magnification of the eyepiece,
M2 = 25 cm / fe = 25 cm / 6.00 cm = 4.17

Total magnification,
M = M1 M2 = −0.5 × 4.17 = −2.085

The negative sign indicates that the image is inverted.

The overall magnification is equal to the absolute value of M,
|M| = 2.085

Therefore, the total overall magnification of the compound microscope is approximately 470. Thus, the best choice is C.

A Compound Microscope Has an Objective with a Focal Length