Electric Field using Ampere's law

[Limabeane14]

Consider the situation shown in Figure P24.1. An electric field of 300 V/m is confined to a circular area d = 11.0 cm in diameter and directed outward perpendicular to the plane of the figure. If the field is increasing at a rate of 22.0 V/m·s, what are direction and magnitude of the magnetic field at the point P, 15.0 cm from the center of the circle?


I know that the direction is upward but how do I find the magnitude?

Thanks.

 

[spaghetti3451]

You need to use Ampere's law, but judging by the simplicity of the problem, i am not sure if you have learned that topic yet.