Determining the direction of the magnetic field

[Physgeek64]

Homework Statement

suppose we have a charging capacitor orientated along the z-axis, such that we have a changing electric field. How do I determine the direction of the associated magnetic field.

Homework Equations

The Attempt at a Solution

I calculated the magnitude of the B field, and my intuition tells me that the magnetic field will loop in the theta direction, but I don't know how to prove that this is the case.

I know that the magnetic field has to be perpendicular to the E-field ( which is in the z direction) and must form a closed loop. But how would you know that the field is not in the -theta direction? Many thanks :)

 

[kuruman]

I know that the magnetic field has to be perpendicular to the E-field ( which is in the z direction) and must form a closed loop. But how would you know that the field is not in the -theta direction? Many thanks :)

You know by using the right hand rule. If the increasing E-field is pointing in the z-direction, the B-field will be in the +θ direction. If the increasing E-field is in the -z direction, the B-field will be in the -θ direction.

 

[Physgeek64]

You know by using the right hand rule. If the increasing E-field is pointing in the z-direction, the B-field will be in the +θ direction. If the increasing E-field is in the -z direction, the B-field will be in the -θ direction.

Is that just the right hand thumb rule? Many thanks