A cylindrical region contains a uniform electric field that is parallel to the axis and is changing with time. If r is the distance from the cylinder axis the magnitude of the magnetic field outside the region is:

Question

Quizplus · Accepted Answer

Based on Faraday's law, a changing electric field creates a magnetic field. Since the electric field is parallel to the axis, the magnetic field will be perpendicular to the axis and will form circular loops around the axis. The magnitude of the magnetic field outside the cylindrical region is inversely proportional to the distance from the axis, therefore proportional to 1/r. Hence, the correct answer is B.

A Cylindrical Region Contains a Uniform Electric Field That Is