Hi, 1. The problem statement, all variables and given/known data I ran an experiment to determine Br(r), where Br was the radial magnetic field produced by a magnetic dipole. Having found the magnetic moment of the dipole, I would now like to determine the contribution to the magnetic field of the next order in the expansion (viz. the quadrupole). I have no information on the magnetic moment itself of the quadrupole nor do I possess any information on the current density J. I am interested in a very crude estimation, if possible. I do, however, know that the ratio (magnet's size : distance from Hall's magnetic sensor) was ~1:6, on average. 2. Relevant equations See attachment. First moment is that of the dipole. Second is of the quadrupole. 3. The attempt at a solution Using the formulae in the attachment, I estimated the ratio BD/BQ to be 3. Hence, the contribution of the dipole order to the magnetic field was 3 times that of the quadrupole order. I performed the estimation thus: BD = 2*1/2*mD/R3, whereas BQ = 3/2R3 * 2 * 4/3 * mD * 1/6 It seems too small a ratio to me. Could anyone please help me determine whether this is indeed reasonable? I'd truly appreciate some prompt advice.