Find the Electric Field strength

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SUMMARY

The discussion focuses on calculating the electric field strength in a copper cable carrying a 50A current with a radius of 0.003m and a resistivity of 1.7x10^-8 Ohm/m. The key equations utilized include the current density formula, \(\vec{\mathbf{J}} = \frac{I}{A}\), and Ohm's law, \(\mathbf{J} = \sigma \mathbf{E}\). The user attempts to relate current density to electric field strength through the work-energy theorem and voltage drop. The correct approach involves applying Ohm's law directly to find the electric field.

PREREQUISITES
  • Understanding of electric current and current density
  • Familiarity with Ohm's law and resistivity
  • Basic knowledge of electric fields and voltage
  • Ability to manipulate equations involving resistivity and geometry of conductors
NEXT STEPS
  • Study the derivation of Ohm's law in different materials
  • Learn about the relationship between electric field and current density in conductors
  • Explore the concept of resistivity and its dependence on material properties
  • Investigate the application of the work-energy theorem in electric circuits
USEFUL FOR

Students studying electromagnetism, electrical engineers, and anyone involved in circuit design or analysis who needs to understand electric field calculations in conductive materials.

Zorba
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Homework Statement


"A copper cable carrying 50A current has radius 0.003m. What is the electric field if copper has a resistivity of 1.7x10^-8 Ohm/m?"

Homework Equations


Formula for current density etc.

The Attempt at a Solution



So I write:
\vec{\mathbf{J}} = n|q|v_d = \frac{I}{A}

And then:
\vec{\mathbf{J}} \cdot \rho = \frac{I}{A} \cdot \frac{RA}{L} = \frac{V}{L}

And now do I just apply the work energy theorem?:
\int \vec{\mathbf{E}} \cdot d\vec{\mathbf{l}} = \Delta V_{ab}

It kind of feels as though I'm completely off tbh...
 
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Use Ohm's law \mathbf{J}=\sigma \mathbf{E}.
 

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