Magnetic flux through metal

1. Apr 1, 2007

jenner7231

I need help solving this question:

The magnetic flux through a metal ring varies with time t according to B = 3( at 3 - bt 2) Tm2, with a = 2.00 s-3 and b = 6.00 s-2. The resistance of the ring is 3.20 . Determine the current induced in the ring at t = 1.00 s.

I know that you have to take the integral of B. The equation that I came up with is emf=-n*integral of B*di/dt

I don't know if that is right though..help!

2. Apr 2, 2007

GmL

Well if you have the area of the ring, then you can use the equation

emf = - d/dt (mag flux)

where mag flux is B (magnetic field) * A (area) * cosine of the angle between them.

If area is constant and the angle between the area vector and magnetic field is zero, we are left with the derivative of B, which is simple to solve. Plug in t=1.00s and multiply everything out and you have emf.

Having solved for emf, just divide by the resistance to find current.

Tell me if this helps.