Electric field in a wire with same current as another wire

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SUMMARY

The discussion centers on calculating the electric field strength required for a 2.0-mm-diameter nichrome wire to carry the same current as a 1.0-mm-diameter gold wire with an electric field strength of 0.0095 N/C. The resistivities used are ρn = 100 x 10-8 Ωm for nichrome and ρg = 2.44 x 10-8 Ωm for gold. The derived formula for the electric field in the nichrome wire is En = (Eg * Ag * ρn) / (ρg * An), resulting in an electric field strength of 0.0973 N/C. The user reports that this answer is not accepted by Webassign, prompting a request for assistance in identifying potential errors.

PREREQUISITES
  • Understanding of Ohm's Law (V = IR)
  • Familiarity with the formula for resistance (R = ρL/A)
  • Knowledge of electric field concepts (V = E * Δs)
  • Basic proficiency in algebra and unit conversions
NEXT STEPS
  • Review the calculation of current in wires using the formula I = EA/ρ
  • Investigate the impact of resistivity on current flow in different materials
  • Learn about the relationship between electric field strength and wire diameter
  • Explore troubleshooting techniques for homework problems in physics
USEFUL FOR

Students studying electrical engineering or physics, particularly those focusing on electromagnetism and circuit analysis. This discussion is beneficial for anyone working on problems related to current flow in conductive materials.

ricky25j
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Homework Statement


For what electric field strength would the current in a 2.0-mm-diameter nichrome wire be the same as the current in a 1.0-mm-diameter gold wire in which the electric field strength is 0.0095 N/C?

dn = .002m
dg = .001m
Eg = .0095 N/C

ρn = 100 * 10-8 Ωm
ρg = 2.44 * 10-8 Ωm

Homework Equations


V = IR
R = ρL/A
V = E * Δs

The Attempt at a Solution


[/B]
First, I found a general equation for current in a wire:

V = IR
I = V/R
I = (E*Δs)/(ρL/A)
I = EA/ρ

Then, I used this to find the current in the gold wire (and by extension, the nichrome wire).

In = Ig = Eg * Ag / ρg

I then used the I = EA/ρ equation to find an expression for the electric field in the nichrome wire, and plugged in the above value for the current.

En = In * ρn / An
En = (Eg * Ag * ρn) / (ρg * An)

I then plugged in the values and solved.

En = [(.0095 N/C)(π*(.001m)2/4)(100*10-8Ωm) / [(2.44*10-8Ωm)(π*(.002m)2/4)]

= .0973 N/C

Webassign is not accepting this answer. Does anyone know where I went wrong?
 
Last edited:
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Welcome to PF!

Your work looks correct. Did you get the values of the resistivities from you textbook?
 

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