# I'm doing my AS biology exam next week and I dont get how to do magnification questions at all! Help! (:

(:

Posted Wed 9th May, 2012 @ 19:12 by Abbie Marshall

If your asked to find the magnification, or the actual (real length) of the specimen, use the formula

magnification = image lenght / real length

Its helpful to remeber that magnification is how big something looks (image length) compared to how big it really is

say you wanted to find the real length of a bacterium and you measure the image length to be 30 mmm and told the magnification was 10000, you would rearrange the above equation to say real length = image length/ magnifiaction

you should get the answer as 0.003 m remeber alwasys convert / measure in mm.

Note magnification is different to resolution

Good luck with your exa,m :) x

Answered Wed 9th May, 2012 @ 19:20 by Edward Pinches

Thankyou soo much! :) x

Answered Wed 9th May, 2012 @ 19:23 by Abbie Marshall

FIne hunn hope you understand it better youll be fine :) x

Answered Wed 9th May, 2012 @ 19:30 by Edward Pinches

yes thankyou!! It was just confusing on how to change the units from cm to um ahaha :) I hope so! :) x

Answered Wed 9th May, 2012 @ 19:36 by Abbie Marshall

Good :) always have them in mm ... um is micro meteres and is *10-6.. trust me youll be fine x

Answered Wed 9th May, 2012 @ 19:41 by Edward Pinches

ohh okay! .. thankyou again haha :) x

Answered Wed 9th May, 2012 @ 19:43 by Abbie Marshall

The equation for magnification is:

Actual size = Image Size / Magnification.

Often they give you a diagram of a cell and ask you to work out the actual size of a mitochondria for example. They will also tell you the magnification. They will also give you the unit they want the answer in.

Eg: The magnification is 1200. Find the actual size in micrometres.

Firstly measure the diagram. Say that it is 50mm:  50/1200 = 0.0416mm

Then to convert it to micrometres: 0.416 x1000 = 41.6micrometres

Another example that is slightly different:

The diagram has a scale showing that 20 micrometres is the width of the whole thing and wants you to find the actual length of structure C.

1: measure the image size of the diagram. It is 55mm

2: convert this to micrometres so it is the same as the scale. 55 x 1000 = 55000micrometres

3: Divide the image size by the actual size to get magnification. 55000/20 = 2750

4: Measure the length of structure C. It is 10mm

5: Again convert this to micrometres. 10 x 1000 = 10000

6: Divide the image size by magnification to get actual size. 10000/2750 = 3.6micrometres.

So just remember the formula and how to rearrange it and also how to convert millimetres to micrometres to nanometres and back again.

Hope this makes sense and helps! Good luck with your exam!

Answered Wed 9th May, 2012 @ 19:45 by Sophie

yes it does thankyou!! :)

Answered Wed 9th May, 2012 @ 19:49 by Abbie Marshall

sorry to be a pain ;) but i have this question.. This diagram shows the cell magnified 1000 times. Calculate the actual length of the cell between points P and Q. Give your answer in um. Show your working. (P and Q is 6.1 am ) how would i do this ? x

Answered Wed 9th May, 2012 @ 19:56 by Abbie Marshall

6.1cm*

Answered Wed 9th May, 2012 @ 19:57 by Abbie Marshall

hahah no botherr .. mag=img/real

therefore real =img/mag

6.1 cm = 61mm

61/1000 =0.0061mm :) x

Answered Wed 9th May, 2012 @ 20:37 by Edward Pinches

Thankyou!! haha :) x

Answered Wed 9th May, 2012 @ 20:40 by Abbie Marshall

Hahah its ok! :) x

Answered Wed 9th May, 2012 @ 20:57 by Edward Pinches

what exam boards are you doing?

Answered Sun 13th May, 2012 @ 12:10 by Georgina

im doin aqa x

Answered Sun 13th May, 2012 @ 12:22 by Edward Pinches