Solving Resistivity Question: Determine Shunt Length

[brenfox]

Homework Statement

Determine the length of the shunt if the c.s.a of the copper is 25cm^2.

Homework Equations

R = ρ l/a
Resistance of shunt is 0.5μΩ

The Attempt at a Solution

Transposing to find l.
l = AR/ρ
=25^2x10^2 x 0.5x10-6/1.7x10-8
=7.4mm is the length of the shunt. Does this look feasible? Any guidance will be well received.

 

[mfb]

Please use units, this makes it much easier to check which number you put where.
I think there is a factor of 10 missing somewhere.