Current density and vector potential

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SUMMARY

The discussion focuses on determining the current density that corresponds to the vector potential A(r)=(-kμ/2π)ln(r/a) in cylindrical coordinates. The user consistently arrives at a zero current density, leading to confusion regarding potential errors in their calculations. The relationship between the magnetic field B and the current density J is explored, specifically using the equations B=∇×A and J=(∇×B)/μ. The user is reminded that the expression r/r is undefined at r=0, which may impact their calculations.

PREREQUISITES
  • Understanding of vector potentials in electromagnetism
  • Familiarity with cylindrical coordinates
  • Knowledge of the curl operator in vector calculus
  • Proficiency in applying Maxwell's equations
NEXT STEPS
  • Study the derivation of vector potentials in cylindrical coordinates
  • Learn about the curl operation and its physical significance in electromagnetism
  • Investigate the implications of singularities in vector fields
  • Explore the relationship between current density and magnetic fields in detail
USEFUL FOR

This discussion is beneficial for physics students, particularly those studying electromagnetism, as well as educators and researchers interested in vector potentials and current densities in cylindrical coordinates.

oddiseas
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Homework Statement



What current density would produce the vector potential
A(r)=(-kmu/2pi)In(r/a) (in the z direction)

where k is a constant, in cylindrical coordinates?

Homework Equations





The Attempt at a Solution



i have done this three times and i get zero current density.So i am wondering if i am making a mistake, there is only one component for A the z component so when i use B=grad*A, i get a field in the fita direction, then when i use J=(grad*B)/mu i get zero.
 
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oddiseas said:

Homework Statement



What current density would produce the vector potential
A(r)=(-kmu/2pi)In(r/a) (in the z direction)

where k is a constant, in cylindrical coordinates?

Homework Equations





The Attempt at a Solution



i have done this three times and i get zero current density.So i am wondering if i am making a mistake, there is only one component for A the z component so when i use B=grad*A, i get a field in the fita direction, then when i use J=(grad*B)/mu i get zero.

Hint: \frac{r}{r} is undefined at r=0:wink:
 

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