My Exam#1

Hi,

Wish you good time. My Semester exams started. Today I wrote my favorite paper "microbiology". The question was easy. But, the answers were only little tough :P Anyways, I managed to do well. :)

There in the question paper, I had a wonderful question! I started thinking, "cha, we had never thought like this..!" The question was very simple, but, I didn't know the answer. Even now I'm not sure about the answer.

I had been using microscopes, mostly optical - bright field microscopes over a past few years, may be from my 11 th class I can say. I had read about Dark field microscope too. But, I had never thought of converting a bright field microscope to a dark field one! But, this question paper setters, really they are great. I felt  like saying, "what an idea sir ji", on seeing the question. :P :P :D

The question was, "can you convert a bright field microscope to a dark field microscope? If so how?"

I don't know the answer for this question. I thought like " yes it may be possible, but.. how? something like changing the light source position?"

I left space and proceeded with the next question. After finishing all the questions, I came to the space. 

I wrote like this:

" In bright field microscope, we get dark images over bright background; In dark field, bright images in dark background. Yes it is possible to convert a bright field microscope to dark field by changing the position of the light source" :P :P :P

I know this is wrong, but, anyways I filled the gap! Came home and searched for the answer. But, I didn't get the correct answer. 

The correct answer might be:

" Conversion is possible by changing the condenser lens of the bright field microscope, because dark field uses special lenses" 

I'm not sure with this. You know the answer? Can you give me the right answer? 

If your are a science person, who knows about microscopes, kindly answer me! :( :(