PDA

View Full Version : Magnetic Field and Torque


estanton
Nov3-09, 12:32 PM
1. The problem statement, all variables and given/known data

The 10-turn loop of wire shown in the figure lies in a horizontal plane, parallel to a uniform horizontal magnetic field, and carries a 2.0A current. The loop is free to rotate about a nonmagnetic axle through the center. A 50g mass hangs from one edge of the loop.

2. Relevant equations
Torque = r x F
Torque = IA x B


3. The attempt at a solution
My thought was to simply calculate the torque created by the mass and then relate that with an opposite torque provided by the magnetic field. I suspect that I'm calculating the torque created by the hanging mass wrong, since I haven't really dealt with torques in some time.
Torque = r x F -> .025m*.05kg*9.8m/s^2 = .01225 Nm
Torque = IA x B -> Torque/IA = B -> .01225/(2.0A*(.05*.1)) = B = 1.225 T

If someone could help with what I'm overlooking here I would appreciate it.

estanton
Nov3-09, 12:49 PM
never mind, I figured out that I have to use N (number of turns) in with mu.

sahar13
Nov18-09, 03:22 PM
Hey, I tried the same thing you did... how do you factor in the number of turns?

Redbelly98
Nov18-09, 07:19 PM
Welcome to PF :smile:

For a 1-turn loop, the torque is what estanton had before:

T = I AxB

If instead you have 10 loops, can you tell how that affects the torque?