Induced EMF in a coil from a 50Hz power line 10m away

[WY]

Hey
I'm wondering if someone can help me out with this question.

Q: In order to measure the magnetic fields produced by the power lines carrying 50Hz alternating current, a coil consisting of 1500 turns of area 5cm^2 as constructed. Suppose that there is a single power line carrying a current which has an amplitude of 800A and that the coil is 10m from the wire.
a) What is the magnitude of the magnetic field at the coil
I found this using B =[N(mu_0)I]/2R
b) What is the magnitude of the induced emf in the coil?

I'm stumped on B could anyone point me in the right direction? I was using the idea that change in flux over time can be used to find induced emf and that in an alternating curret dI/dt=2*pi*f*I - but the problem is that i don't know where to go from there.

Thanks in advance!

 

[mukundpa]

The magnetic field is not constant.
Write the equation for the current as a function of time.

 

[WY]

thanks for the quick reply - but i don't quite understand how this ties in with finding the emf using the change in flux over the change in time.

 

[WY]

oh i see now! sorry - I wasn't thinking properly! Thanks again :)