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please help me - a level

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please help me - a level

Postby red.ninja13 » Wed Oct 24, 2007 9:51 pm

im doing a learn at home a level in biology (aqa spec b), and theres one part i cant make any sense of, no matter where i look on the net, and as i am doing it learn at home i have no access to microscopes or anything.

i dont understand how to do calculations when looking at stuff through a graticule and stage micrometer, can anyone explain it to me, or give me anywhere with examples i can try and work out myself?

thank you
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Postby blcr11 » Thu Oct 25, 2007 1:59 pm

For measuring the size of things—making use of the scale and reticule:

http://www.ruf.rice.edu/~bioslabs/metho ... uring.html
http://www.ekcsk12.org/science/lelab/mi ... ntlab.html


For counting cells with a graticule:

http://www.ruf.rice.edu/~bioslabs/metho ... nting.html

Alternatively, for cell counting, search for “hemocytometer” or "haemocytometer" and/or try and find an instruction pamphlet from one of the manufacturer’s websites.
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Postby red.ninja13 » Thu Oct 25, 2007 11:16 pm

lets see if i'v got this correct........

1mm = 1000µm

if
1 stage unit = 0.01mm
and
3 graticule units = 1 stage unit

3g = 10µm
1g = 10∕3
1g = 3.33µm


3g = 0.01mm
1g = 0.01∕3
1g = 0.0033mm


so could i use the equation

ng = ns
1g = n/n

then times by 100 to get µm

have i got it? :shock:
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