Imagine that we constrain a rectangular loop to move through a square region where the magnetic field $\vec{B}$ is uniform and downward (in the $-z$ direction), as shown below. Assume that $\vec{B} \approx 0$ outside that region.

We can divide the loop's motion up into five phases:
For each of the five phases, which of the following is true?
-(a) The loop has not yet entered the magnetic field.
A) Current flows clockwise in the loop.
B) Current flows counterclockwise in the loop.
C) Current does not flow in the loop.

Question

Imagine that we constrain a rectangular loop to move through a square region where the magnetic field $\vec{B}$ is uniform and downward (in the $-z$ direction), as shown below. Assume that $\vec{B} \approx 0$ outside that region.
  
We can divide the loop's motion up into five phases:
For each of the five phases, which of the following is true?
-(a) The loop has not yet entered the magnetic field.
A) Current flows clockwise in the loop. 
B) Current flows counterclockwise in the loop. 
C) Current does not flow in the loop.

Quizplus · Accepted Answer

Since the loop has not yet entered the magnetic field, there is no change in magnetic flux through the loop, and thus, according to Faraday's law of electromagnetic induction, no current is induced.

Imagine That We Constrain a Rectangular Loop to Move Through B⃗\vec{B}B

Imagine That We Constrain a Rectangular Loop to Move Through $\vec{B}$