# Biology Magnification Electron Microscope

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#1
Dear all,

I was doing a sample paper today and came upon a mcq question on magnification. It showed an electron micrograph of a beetle, and on the bottom left there was a ------ with 100 micrometers below it. To calculate the magnification it's drawing of image/actual size of image, but what is the significance of this 100 micrometers?

Thank you very much for your time, all help is greatly appreciated!
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1 month ago
#2
Hi there! There is no way of telling what the image size is unless there is some kind of scale, yeah?

So to work out magnification:
Understand this - try not to work like an electric motor - try to think!
DW I'll guide you - magnification is how many times bigger the view in front of your eyes [on the EM] is COMPARED TO the actual size of whatever you are looking, at, happy so far.

So the line is just telling you that that distance [the length of the line] REPRESENTS a distance on the mitochondrion OR lysosome OR whatever the pic shows EQUAL TO 100 um.

Therefore, measure the line with your ruler, then convert to um so if the length of line is e.g. 20 mm, this is equal to 20,000 um but it is showing you an actual size of 100 um.

So how many times bigger r u seeing?......................... ................................ ................................ ................................ ................................ ................................ ..............Yes, well done! ................................ .....................what you are seeing divided by the actual size, happy?

In this e.g. magnification = 20,000 / 100 = 200X [your answer should be much larger than this - the whole point of an electron microscope!]

But oc in place of 20,000 you put the length of the line converted to um.

It was not rocket science was it, it is cell biology!
Last edited by macpatgh-Sheldon; 1 month ago
0
1 month ago
#3
(Original post by thebluhood)
Dear all,

I was doing a sample paper today and came upon a mcq question on magnification. It showed an electron micrograph of a beetle, and on the bottom left there was a ------ with 100 micrometers below it. To calculate the magnification it's drawing of image/actual size of image, but what is the significance of this 100 micrometers?

Thank you very much for your time, all help is greatly appreciated!
It's telling you the scale of the image, without that scale you would have no idea the actual size of the beetle. Is that 5cm representing 5 millimetres or 5 micrometers, you wouldn't be able to tell. The way to work out what the scale is to measure the ----- line . You can then do the actual measurement divided by 100 micrometres to get the magnification. Now you know how much the image is being enlarged by.
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