Scientists studying an anomalous magnetic field find that it is inducing a circular electric field in a plane perpendicular to the magnetic field. The electric field strength is 4.0 mV/m at a point 1.5 m away from the center of the circle. At what rate is the magnetic field changing?

The rate at which the magnetic field changes is  

Explanation:

From the question we are told that

   The  electric field strength is

   The  radius of the  circular region where the electric field is induced is

Generally the induced electric field is mathematically represented as

The  negative sign show that the induced electric field is acting in opposite direction to the change in magnetic field

Where   is the change in magnetic field

So  

substituting values