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1. The problem statement, all variables and given/known data

This is part of a lab report I am doing: Plot a graph of V against I^2 and find the e/m ratio from the gradient.

2. Relevant equations

e/m = 2V/B^2 r^2 where B is magnetic field, r is radius of electron beam

B = U (4/5)^(3/2) nI/R where U is magnetic constant, n is no. of turns per coil, R is radius of Helmholtz coils

3. The attempt at a solution

I'm not sure what exactly to do once I get the gradient!

Many thanks if anyone can help and feel free to ask if I havn't provided enough info :)

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# Homework Help: Finding e/m ratio

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