Question

A copper hoop is held in a vertical east-west plane in a uniform magnetic field whose field lines run along the north-south direction. The largest induced emf is produced when the hoop is?

A) rotated about a north-south axis
B) rotated about an east-west axis
C) moved rapidly, without rotation, toward the east
D) moved rapidly, without rotation, toward the south
E) moved rapidly, without rotation, toward the northwest

Answer 1

The largest induced emf in the copper hoop is produced when it is rotated about an east-west axis, as this orientation allows for the maximum change in magnetic flux, in accordance with Faraday's law of electromagnetic induction.

Step-by-step explanation:

The student's question pertains to the phenomenon of electromagnetic induction, specifically in the context of a copper hoop in a magnetic field. The largest induced emf in the copper hoop will be produced when the hoop is rotated about an east-west axis. This is because rotating the copper hoop along the east-west axis allows for the maximum change in magnetic flux through the loop, which according to Faraday's law induces the greatest emf.

When the copper hoop is in a vertical east-west plane and the magnetic field is north-south, if rotated about a north-south axis or moved without rotation towards any direction, there would be no change or a lesser change in the magnetic flux, and thus a smaller or no induced emf, respectively.