1. The problem statement, all variables and given/known data Alright so i'm writing a lab report and im running into a problem of finding the error on this value. I am measuring the magnetic susceptibility of a couple of samples. My lab manual and instructor told me the error on the force is related to the error on the derivative of the magnetic field alone and not on the mass or the change in mass. The trouble is I am measuring the force and calculating the magnetic susceptibility. The value of interest to me is the magnetic susceptibility and I don't know how to get the error on the magnetic susceptibility. 2. Relevant equations Fx= 0.5/µ0 * χm*m* (dB^2)/(dx) Thus χm = (2* Fx* µ0)/(m*(dB^2)/(dx)) 3. The attempt at a solution I know the error on (dB^2)/(dx) and using propagation of error, I calculate the error on the force. Should I use the propagation of error again to find the error on the magnetic susceptibility with only F and (dB^2)/(dx) contributing to the error?? Edit: I think this should have been in the introductory physics forum, my mistake.