Aperson has many convex lenses with only two different focal lengths (short and long) which configuration makes the best microscope (built correctly)?
a. a short focal length objective and a short focal length eyepiece.
b. a long focal length objective and a short focal length eyepiece.
c. a long focal length objective and a long focal length eyepiece.
d. a short focal length objective and a long focal length eyepiece.

Option b. A long focal length objective and a short focal length eyepiece

Explanation:

A microscope is an optical instrument which is used to get magnified images of the objects that can not be seen with naked eyes.

Therefore, a good microscope is characterized by the degree of magnification it provides and the magnification of a lens is given by the relation:

From the above relation it is clear that higher degree of magnification can only be achieved by having greater focal length of objective lens and smaller focal length of eyepiece.

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