In the Feynman disc paradox, turning off one of these devices transfers angular momentum to a disc within one of these devices. Particles gain a phase shift in their wavefunctions after traveling on either side of one of these devices in the Aharanov-Bohm effect. Vector fields with zero divergence (-5[1])are typically named after these devices. (15[1])One constructs an Amperean (*) square perpendicularly crossing the surface of these devices to show that the magnetic field inside one of these devices (-5[1])equals the product of mu nought, the current through the device, and the number of loops. (10[1]-5[1])A uniform (-5[1])magnetic (10[1])field is produced in the interior (-5[1])of, for 10 points, what kind of electromagnet, which consists of a long, helical coil of wire? (10[1])■END■ (10[2])