Calculating Maximum Torque of Copper Wire Loop

[J89]

Homework Statement

A copper wire is 9.00 m long and has a cross-sectional area of 1.00 10-4 m2. This wire forms a one turn loop in the shape of a square and is then connected to a battery that applies a potential difference of 0.100 V. If the loop is placed in a uniform magnetic field of magnitude 0.600 T, what is the maximum torque that can act on it? The resistivity of copper is 1.7 10-8 · m.

Homework Equations

T=BIANsin(theta)
I=V/R

The Attempt at a Solution

First solve for R, whicn =
Resistivity*L/A = 1.7e-8*9/(1e-4)
= .00153 ohms

then solve for current (I) = I=V/R = .100/.00153 = 65.359

Then plug in the equation for torque = T=NBIAsin(theta)
however I got.00392, but it's wrong, the answer is 198.53..I know it has something to do with A, but don't know what. Someone please help!

 

[collinsmark]

Then plug in the equation for torque = T=NBIAsin(theta)
however I got.00392, but it's wrong, the answer is 198.53..I know it has something to do with A, but don't know what. Someone please help!

Yes, you're right! It does have something to do with A.

Your equation,
T=NBIAsinθ,
involves a wire loop. What does A refer to in in this equation? (Yes it is an area, but the area of what?) It's not the cross-sectional area of the wire itself that forms the loop. It's the area of something else. (Hint: think "loop" [and not necessarily a circular loop -- just any old loop -- perhaps one that's even rectangular or square].)