How Do You Calculate Electric Energy Density Near a Copper Wire?

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SUMMARY

The discussion focuses on calculating the electric energy density at the surface of a 3.4 mm diameter copper wire carrying a 28 A current. The relevant equation used is u = (1/2) ε0 E², where E is derived from the electric field equation for an infinite line charge. The challenge lies in determining the charge density (λ) for the copper wire, which is essential for calculating the electric field inside the wire. The assumption is made that the electric field at the surface is equivalent to that inside the wire.

PREREQUISITES
  • Understanding of electric energy density and its formula, u = (1/2) ε0 E²
  • Knowledge of electric fields, particularly for infinite line charges
  • Familiarity with the properties of copper, including its conductivity
  • Basic principles of current flow in conductive materials
NEXT STEPS
  • Calculate the electric field inside a copper wire using the formula E = λ / (ε0 2 π r)
  • Research the charge density (λ) for copper based on its conductivity and current
  • Explore the relationship between current, charge density, and electric field in conductive materials
  • Learn about the implications of electric energy density in practical applications, such as power transmission
USEFUL FOR

Students studying electromagnetism, electrical engineers, and anyone interested in the behavior of electric fields in conductive materials.

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Homework Statement


Calculate the electric energy density at the surface of a 3.4 mm diameter copper wire carrying a 28 A current.

Homework Equations


u = (1/2) ε0 E2

The Attempt at a Solution


With the electric energy density equation, I substituted in the equation for the electric field for an infinite line charge:

u = (1/2) ε0 ( λ/ (ε0 2 π r ))2

I have all the information except for the charge density, λ. I know that it's a copper wire, but how can I find what λ is with that information?
 
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I think that you are supposed to assume that the electric field at the surface of the wire is the same as the electric field inside the wire. The electric field inside the wire pushes the electrons through the copper.

Can you determine E inside the wire from the current, the diameter of the wire, and the properties of copper?
 
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