How Does Changing Length and Area Affect the Resistance of Copper Wires?

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SUMMARY

The resistance of a copper wire is determined by the formula R = ρL/A, where ρ represents resistivity, L is the length, and A is the cross-sectional area. In the discussion, a second copper wire with double the length (2L) and half the area (1/2 A) is analyzed. The new resistance R' is calculated as R' = ρ(2L)/(A/2), simplifying to R' = 4ρL/A, which indicates that the resistance quadruples. The resistivity of copper is noted as 1.72 x 10-8 Ω·m.

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  • Understanding of electrical resistance and Ohm's Law
  • Familiarity with the concept of resistivity
  • Basic knowledge of algebra for manipulating equations
  • Knowledge of the physical properties of copper
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zelda1850
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Homework Statement



a copper wire of length of length L and cross sectional area A has resistance R. A second copper wire at the same temperature has a length of 2L and a cross sectional area of 1/2 A. what is the resistance of the second copper wire?

Homework Equations



R = pL/A

L = 2
A = 1/2
p = how do i find p

The Attempt at a Solution



p stand for resistivty but how do i know it in this problem
 
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In the relevant equation replace L by 2L and A by A/2 to get new resistance.
 


oh should the answer come out to be 1R
 


yes.
 


zelda1850 said:
oh should the answer come out to be 1R
No.
New resistance R' = ρ*2L/A/2 = ...?
 


i think p would be 1.72 x 10 exponent -8 since it is on copper
so i do 1.72x10 exponent -8 * 2 m/ 2 a is that the right equation?
 

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