# Current in a rectangle on a hinge

1. Mar 2, 2013

### lodovico

1. The problem statement, all variables and given/known data
Figure 29-36 shows a rectangular, 15-turn coil of wire, 10 cm by 5.0 cm. It carries a current of 0.90 A and is hinged along one long side. It is mounted in the xy plane, at an angle of 30° to the direction of a uniform magnetic field of 0.50 T. Find the magnitude and direction of the torque acting on the coil about the hinge line.

2. Relevant equations

$\tau$=μ × B
μ=NiA

3. The attempt at a solution

I dont know how to approach this. I tried to plug in numbers into ^ formula

2. Mar 2, 2013

### TSny

If you'll show more details of how you tried the calculation, we will be able to see where you're having trouble.

3. Mar 2, 2013

### lodovico

τ=μ × B
μ=NiA

τ=NiABsin30
τ=(15)(.9)(.1*.05)(.5)sin30

τ=.16875 Nm

4. Mar 2, 2013

### TSny

See if you can figure out why the 30o is not correct here. You'll need to think about the direction of $\vec{\mu}$