Ohm's Law: Help please and thank you

[Malaya]

Homework Statement

A cylindrical copper cable carries a current of 1300 A. There is a potential difference of 1.6 10-2 V between two points on the cable that are 0.38 m apart. What is the radius of the cable?

I=1300A
V=1.6e-2 V
l=0.38m
rho=1.7e-8(resistivity of copper)
r=?

Homework Equations

V=IR
Where: V=voltage, I=Current, R=Resistance

R=rho* L/r^2pie
Where: R= resistance, rho=1.7e-8(resistivity of copper), Length in meters, r=radius

The Attempt at a Solution

1. Find Resistance.
V=IR
1.6e-2V=1300A*R
R=1.23E-5 ohms

then I used:
R=rho* L/rpie^2
1.23E-5 ohms=1.7e-8*(0.38m/r^2pie)
2.09e-13=0.38m/r^2pie
6.57e-13=0.38m/r^2
6.57e-13*r^2=0.38m
5.78e11=r^2
r=760333.43m

what do I keep doing wrong??

 

[LowlyPion]

1.23E-5 ohms=1.7e-8*(0.38m/r^2pie)
2.09e-13=0.38m/r^2pie

That step is woefully wrong.

Perhaps if you rewrote it

r²= 1.7*10^-8*(.38)/(π*1.23*10^-5)

 

[nlightner]

Based on your calculations, it seems like you are using the correct equations and correctly plugging in the given values. However, there may be a mistake in your algebra or in converting units. Remember to check your units and make sure they are consistent throughout the problem. Also, be careful with your use of pi - it should be squared in the equation for resistance. Another potential issue could be with the given values - double check to make sure they are accurate and in the correct units. If you are still having trouble, try breaking down the problem into smaller steps and double check each step to identify where the mistake may be occurring.