A long solenoid is surrounded by a circular coil. The solenoid is replaced with an ideal toroid that produces the same average magnetic field in its interior as was present in the solenoid (and no magnetic field outside its enclosed region). The emf induced in the coil if the current in the toroid changes at the same rate is
A) considerably greater than for the case of the solenoid.
B) approximately equal to the case of the solenoid.
C) considerably less than for the case of the solenoid.
D) zero because there is no magnetic field at the location of the coil.

Question

Quizplus · Accepted Answer

The magnetic field inside the toroid is the same as that inside the solenoid, so the emf induced in the coil will be the same in both cases.

A Long Solenoid Is Surrounded by a Circular Coil