# A conducting loop is halfway into a magnetic field. Suppose the magnitude of the magnetic field...

## Question:

A conducting loop is halfway into a magnetic field. Suppose the magnitude of the magnetic field begins to increase rapidly in strength. What happens to the loop?

a) The loop is pushed upward, toward the top of the screen.

b) The loop is pushed downward, toward the bottom of the screen.

c) The loop is pulled to the left, into the magnetic field.

d) The loop is pushed to the right, out of the magnetic field.

e) The tension in the wires increases, but the loop doesn't move.

## Electromagnetic induction

According to the Faraday-Lenz law (law of electromagnetic induction), the variation of the magnetic field flux through a conductive loop will produce an electromotive force in the loop whose effects, within the loop, are opposite to the variation of the magnetic flux that originates it.

If initially the external magnetic field was constant, then no electric current circulated through the loop. When the intensity of the external magnetic field increases rapidly, an induced electric current appears in the loop that generates a magnetic field. Within the loop the induced magnetic field is contrary to the external magnetic field. It is as if two equal magnetic poles were joined. As equal magnetic poles repel, then the loop will move to the right outside the external magnetic field (option D).