Coaxial cables and displacement current

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SUMMARY

The discussion centers on the behavior of magnetic fields generated by coaxial cables carrying alternating current. Specifically, when an electric current i(t) = Imax * cos(w*t) flows through the inner core and an inverse current flows on the outer surface, the magnetic field B outside the cable (for r > b) is confirmed to be zero. This conclusion arises from the cancellation of currents, leading to both zero current and zero displacement current effects in the external region.

PREREQUISITES
  • Understanding of electromagnetic theory, specifically Maxwell's equations.
  • Familiarity with coaxial cable structure and properties.
  • Knowledge of alternating current (AC) behavior and its effects on magnetic fields.
  • Basic concepts of displacement current in electromagnetic fields.
NEXT STEPS
  • Study Maxwell's equations in detail, focusing on displacement current.
  • Explore the properties and applications of coaxial cables in electrical engineering.
  • Learn about the implications of alternating current on magnetic field generation.
  • Investigate the concept of magnetic field cancellation in various configurations of current-carrying conductors.
USEFUL FOR

Electrical engineers, physics students, and professionals working with electromagnetic fields and coaxial cable applications will benefit from this discussion.

DaTario
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Hi All,

Consider a situation in which a coaxial cable have electric current i(t) = Imax * cos(w*t) flowing through its cilindrical inner cylindrical core (with radius a) and the inverse current flowing on its surface cover (with radius b).
I would like to know if it is correct to say that, outside de cable (r > b), we will see not only zero current effects (due to obvious cancelation) but also zero displacement current effects.

I hope my explanation could have achieved the necessary clarity.

Best wishes,

DaTario
 
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By "effects"in the OP I mean effects in the magnetic field B generated by the cable. In other word my question is:
with current i varying in time, the magnetic field produced by the cable outside it is zero?
 

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