Resistance Problem Find Length of Wire

[m_physics]

1.Problem
A current of 0.76A flows through a copper wire 0.44mm in diameter when it is connected to a potential difference of 15V. How long is the wire?
2. Homework Equations (Missing any?)
V=IR
R=row(L/A)
A=pieD^2/4
row=resistivity=p
p of copper=1.72 x 10^-8
3.Attempt
Pretty sure conversion is wrong.
V=IR
15=(.76a)R
R=19.737

D=.44mm mm to m
4.4 x 10^-5m

A=pieD^2/4
A=(3.14)(4.4 x 10^-5)^2/4
A=1.512 x 10^-9

Plug back into the resistance equation for L

R=row(L/A)R=row
19.737=(1.72 x 10^-8)(L/1.512 x 10^-9)
2.999x10^-8=1.72 x 10^-8L
L=(2.999x10^-80)/(1.72 x 10^-8)
L=1.744m

Correct Answer: 170m

 

[Brian_C]

You made an error in converting the diameter of the wire from millimeters to meters.