# Calculating magnification Watch

1. hi evry1,
im having trouble with calculating magnification, basically using the eqn:
magnification=observed/actual

its the part where you have to jump between units where im having trouble.
For example the diameter of this cell from A to B is 40micrometers. Calc the magnification of this drawing.

The distance from A to B i measured to be 5.6cm. The answer is 1500 but i have no idea how this was done.

thanks
2. How would you start the qu?
3. er well mag = image/ actual object

image is 5.6cm = 56mm = 56 000 micrometres = 56 000 000 nanometers

56 000 000 /40 = 1 400 000

have i done something really stupid/ wrong here?
4. I would have converted both to metres, so got
(5.6 x 10^-2)/(40 x 10^-9) = 1,400,000.
Are you sure the diameter is in nanometres, and not micrometres?
5. sorry my mistake, its in micrometers.
but i still cant get the right answer .

do you think we might have to round up the length to 6cm as that would give the right answer.
6. ye that would be right
7. so the question now is that if for example the observed length of a cell is like 3.6 cm, would i round it up to 4 or use 3.6 as the figure.
also in the markscheme it doesnt say anything about allowing any other answers.

thanks
8. I would use the accurate value you measured. Normally in exams they would expect you to measure it accurately and use that measurement in your calculations.
9. use the one that you measured exactly. in the mark schemes i read for working out the magnification, there's always a range of values that it could be- unless the thing you're measuring is clearly to the nearest mm.

maybe you measured the image inaccurately? they sometimes ask you to measure the diameter of an organelle at its widest point or something...
10. No, it was definatley 5.6cm from A to B as it said in the question and there was a dotted line joining the two points.
is there anything wrong with the method i used?

thanks
11. nope there wasnt anything wrong with your method. except the bit where you mistakenly took micrometers for nanometers lol.

so maybe the mark scheme is wrong then; they are constantly updated when the are used to mark the papers as they can sometimes have mistakes. i wouldnt worry about it, what you did is right.
12. I have a possible solution as to where you could have gone wrong. If you are working off a small printed A5 test booklet then the answer in the mark scheme will not agree as that refers to the A4 version
13. Magnification = observed size/ actual size

you have to convert the values into the correct values so that you get the right answer.

5.6cm = 56mm
40 micrometers= 0.04 mm 1mm= 1000 micrommeters
so the maginification is 56/0.04= 1400
1micrometer= 1000 nm
14. (Original post by minikitkat)
Magnification = observed size/ actual size

you have to convert the values into the correct values so that you get the right answer.

5.6cm = 56mm
40 micrometers= 0.04 mm 1mm= 1000 micrommeters
so the maginification is 56/0.04= 1400
1micrometer= 1000 nm
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