Question

Which of the following is incorrect about a compound microscope?
A) It consists of two convex lenses.
B) The Objective has smaller focal length than the eyepiece.
C) The objective forms a real magnified image
D) The final image is real and much magnified.

Answer 1

Hint: To answer this question we should start with the definition of a compound microscope. We can then make a ray diagram for the compound microscope and then see if the options in the questions hold true or not.

Complete solution:
To answer this question, we have to start with the definition of a compound microscope. So let us see what a compound microscope is.
A compound microscope is a high power (high magnification) microscope that uses a compound lens system. A compound microscope has two different types of lens i.e. the objective lens and the eyepiece lens. Both these lenses are compounded to obtain a high magnification.

It is based on the principle that whenever a small specimen e.g a cell, is placed just beyond the focus of its objective lens, a virtual, inverted, and highly magnified image of the object is formed at the least distance of distinct vision from the eye held close to the eyepiece.

The above diagram is for an image formed at least distance of distinct vision. From the results of this ray diagram, it is clearly evident that
It consists of two convex lenses.
The Objective has a smaller focal length than the eyepiece.
The objective forms a real magnified image
Hence we can say that option (D) is the only option that does not hold true for a compound microscope.

So our answer will be an option (D).

Note: A compound microscope is used in pathology labs, in forensic laboratories, by students in schools and colleges, and to study the cell of various plants and animals.
While answering any question with options be careful in reading the question. The question here is to find the incorrect option. So go only for the one which is not true for a compound microscope.