Determining the direction of the magnetic field

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SUMMARY

The discussion centers on determining the direction of the magnetic field generated by a charging capacitor aligned along the z-axis, which produces a changing electric field. Participants confirm that the magnetic field (B-field) is perpendicular to the electric field (E-field) and forms closed loops. The right-hand rule is established as the definitive method for determining the direction of the B-field: if the E-field points in the positive z-direction, the B-field will loop in the positive theta direction, and vice versa for the negative z-direction.

PREREQUISITES
  • Understanding of electromagnetic fields, specifically electric (E-field) and magnetic (B-field) relationships.
  • Familiarity with the right-hand rule for determining vector directions in electromagnetism.
  • Basic knowledge of capacitor behavior in electric circuits.
  • Concept of closed loops in magnetic fields.
NEXT STEPS
  • Study the right-hand rule in detail to master its application in electromagnetism.
  • Explore Maxwell's equations to understand the relationship between electric and magnetic fields.
  • Investigate the behavior of capacitors in AC circuits and their impact on electric and magnetic fields.
  • Learn about the Biot-Savart law for calculating magnetic fields generated by current-carrying conductors.
USEFUL FOR

Students and professionals in physics, electrical engineering, and anyone interested in understanding the principles of electromagnetism and the behavior of electric fields in relation to magnetic fields.

Physgeek64
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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 :)
 
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Physgeek64 said:
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.
 
kuruman said:
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
 

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