A circular loop is placed in a magnetic field, with the plane of the loop perpendicular to the field lines. Which of the following will not cause a current to be induced in the loop?
A) Crushing the loop.
B) Rotating the loop about an axis perpendicular to the field lines.
C) Pulling the loop out of the field.
D) Keeping the orientation of the loop fixed and moving it along the field lines.

Question

Quizplus · Accepted Answer

According to Faraday's law of electromagnetic induction, a current is induced in a loop if the magnetic flux through the loop changes. Crushing the loop (A) changes the area and thus the flux. Rotating the loop (B) changes the angle between the field lines and the normal to the plane of the loop, altering the flux. Pulling the loop out of the field (C) changes the amount of field the loop is exposed to, again changing the flux. However, keeping the orientation of the loop fixed and moving it along the field lines (D) does not change the flux through the loop, as both the area and the angle relative to the field lines remain constant, and thus, no current is induced.

A Circular Loop Is Placed in a Magnetic Field, with the Plane