Flux through rotating ring

dikmikkel

1. The problem statement, all variables and given/known data
A ring can rotate about a horizontal axis(x), and a diameter placed on the x-axis. A uniform field is perpendicular to the ring -B0*y. The diameter of the ring is D. it spins with constant angular velocity ω around the x-axis. At at time t = 0 the ring is entirely in the xy plane

How do i find the flux change per time? And what does it mean that it can rotate around a diameter.
I've attached a figure.


2. Relevant equations
[itex] Flux = \int \vec{B}\cdot d\vec{a}[/itex]


3. The attempt at a solution
At a time t = 0 the flux through the loop is 0 and i tried to write a solution using that B is constant:
[itex] Flux = B\int sin(\theta (t))d\vec{a}[/itex]
[itex] Flux/dt = B\int cos(\theta(t) ) \omega d\vec{a}[/itex]

Attached Thumbnails

 

dikmikkel

Nwm.
I found out.