Question 18.CE.1: Moving loops in a steady magnetic field The figure shows fou......
Moving loops in a steady magnetic field
The figure shows four wire loops moving at constant velocity \vec{v} relative to a region with a constant \vec{B} field (within the dashed lines). In which of these loops will electric currents be induced?
Sketch and translate An electric current will be induced in a loop whenever the number of \vec{B} field lines through the loop’s area changes.
Simplify and diagram For each case, current should be as follows:
1. The loop is moving into the field region, so the number of \vec{B} field lines through its area is increasing. A current will be induced in the loop.
2. A current will be induced in the loop for the same reasons as (1).
3. The loop is completely within the field region, thus the number of \vec{B} field lines is not changing. As a result, no current is induced.
4. No current is induced for the same reason as in (3).
Try it yourself: What happens to loops 3 and 4 as they are leaving the magnetic field region?
Answer: The number of \vec{B} field lines through each loop will change and a brief current will be induced as the loops leave the \vec{B} field region.
