Help with magnetic forces problem! Is my solution correct?

  • #1

Homework Statement


A wire loop, of mass "m" and radius "r"; in the x-y plane with a current "I" flowing through it in the clockwise direction is in a magnetic field. The field "B" is pointing along the x-axis. The magnetic field will exert a torque on the wire, causing the loop to rotate with a frequency "f".
What is the magnitude of the magnetic field?

Homework Equations


torque = IA x B = I(pi)r^2 x B
torque = r x F = r x (ma) = r x (m(r*alpha))
theta(final)=theta(initial)+omega(initial)*t+(1/2)(alpha)t^2

The Attempt at a Solution



Assuming that the initial angular velocity is zero.
A full revolution -> theta(final)=2*pi
time for a full revolution (period) -> T=1/f

angular acceleration -> alpha = 2*(2*pi)/T^2

torque = rF = r(ma) = r*m(r*alpha) = r^2*m*(4*pi/T^2)

torque = I*A*B = I*pi*r^2*B

r^2*m*4*pi/T^2 = I*pi*r^2*B

B = 4*m/I*T^2
 

Answers and Replies

  • #2
Sorry to bump... but ... can anyone confirm this?
 

Related Threads on Help with magnetic forces problem! Is my solution correct?

Replies
5
Views
574
Replies
1
Views
3K
  • Last Post
Replies
6
Views
1K
Replies
6
Views
2K
Replies
2
Views
982
Replies
6
Views
280
Replies
3
Views
1K
Replies
2
Views
1K
  • Last Post
Replies
8
Views
3K
Top