Question

A person 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.

Answer 1

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

Step-by-step 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:

`magnification, m = (objective lens' focal length)/(eyepiece lens' focal length)`

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.