# Light microscope specimen size

I was going through sample questions for Science Olympiad, and one of the questions went like this:

A cell is observed through a light microscope at 4x magnification. The cell takes up about half of the visual field. What is the approximate length of this organism?

I know from prior knowledge that a cell can be anywhere from $10$ to $100$ micrometers, but I don't know how to figure out a cell's size with the information I'm given. Usually when I do problems like this, I am given the size of the field of view. Is that not needed to solve this problem?

• pob.k12.ny.us/cms/lib/NY01001456/Centricity/Domain/517/… Have a look his should help.. – Polisetty Oct 27 '16 at 2:58
• @Polisetty Those slides just pretty much review what I already know... is there something I missed? – suomynonA Oct 27 '16 at 3:22
• Is this an mcq? since the question says, "approximate", you can assume the fov to be 5mm for 4x. Though it changes also with the magnification of your eyepiece. We were told to remember the fov values for 4x, 10x, 40x, 100x.. approximately - 5mm, 2mm, 0.5mm, 0.2mm These were approximates. This was a long time back.. maybe someone else can answer better.. Here's a full table - seoenterprises.com/shop/pages.php?pageid=12 – Polisetty Oct 27 '16 at 5:45
• @Polisetty thanks for the chart; also what's a mcq? – suomynonA Oct 28 '16 at 1:09
• a 'multiple choice question'. huehuehue. – Polisetty Oct 28 '16 at 1:23