Posted by Mary on Friday, September 28, 2007 at 1:57am.
The maximum torque experienced by a coil in a 0.90 T magnetic field is 8.4 104 N·m. The coil is circular and consists of only one turn. The current in the coil is 3.9 A. What is the length of the wire from which the coil is made?
Please tell me if I am going in the right direction.
Torque = NIAB sin theta
8.4x10^4 = 1 x 3.9 x (pi r^2) x 0.9 x sin theta
How do I find the value of sin theta to plug into the formula?

Physics  drwls, Friday, September 28, 2007 at 2:49am
They give you the maximum torque, and that corresponds to theta = 90 degrees
(sin theta = 1)
Solve for r.
N = 1 in this case
The length of the wre is 2 pi r