A toroidal solenoid has 550 turns, cross-sectional area 7.00cm2 , and mean radius 4.90cm.
Calcualte the coil's self-inductance.
If the current decreases uniformly from 5.00 A to 2.00 A in 3.00 ms, calculate the self-induced emf in the coil.
The current is directed from terminal a of the coil to terminal b. Is the direction of the induced emf from a to b or from b to a?