- #1
grandpa2390
- 474
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edit: wait... I think the discrepancy is that I calculated Coulombs per kg? and the accepted value I was looking at was in abcoulombs per kg. If that is indeed the case, then my answer is indeed close to the accepted value of 1.76 * 10^11 Coulomb/kg. 1. Homework Statement
I am trying to calculate e/m for data I got from a laboratory experiment with a helmholtz coils. I am not sure if I have bad data, or if I have a mistaken unit somewheres. I am getting 1.96 * 1011 after I average all my e/m together. I should be getting 1.76 * 107
Am I doing something wrong, or is it my data? I am not going to put all my data up. I will just put some 1 measurement and please tell me if I am using wrong units somewheres.
Homework Equations
http://badger.physics.wisc.edu/lab/manual2/node10_tf.html
e/m = [PLAIN]http://badger.physics.wisc.edu/lab/manual2/img129.gif2.47 x 1012[PLAIN]http://badger.physics.wisc.edu/lab/manual2/img130.gif[PLAIN]http://badger.physics.wisc.edu/lab/manual2/img131.gif[PLAIN]http://badger.physics.wisc.edu/lab/manual2/img132.gif coulombs/kg
The Attempt at a Solution
my measurement is:
accelerated voltage = 40 volts
current for helmholtz coils = 2.46 Amps
Radius of coil = .33 meters
there are 72 turns on each coil
radius of the electron beam = .039 meters
I get 2.25 * 10^11
is this what my data gives me, or am I using the formula incorrectly? I should get 10^7
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