I am so glad I found the link to this test, so I can reference questions with figures. let me write the problem first, and provide the link at the end, and in between explain where I was stuck. 87) two small pith balls, each carrying a charge q, are attached to the ends of a light rod of length d, which is suspended from the ceiling by a thin torsion-free fiber, as shown in the figure above ( in the link). There is a uniform magnetic field B, pointing straight down, in the cylindrical region of radius R around the fiber. The system is initially at rest. If the magnetic field is turned off, which of the following describes what happens to the system? I found the emf induced around the loop of Radius R, and I integrated from 0 to R to find the torque on the bar, and I multiplied my answer by 2, because there are two fields on the bar of opposite direction ( a loop), which will add to the torque, so I got that the bar will rotate with angular momentum = qBR^2/2, but the correct answer is twice as much. here is it with the figure: http://phys.columbia.edu/~hbar/Physics-GRE.pdf thankyou so much!