# Faraday's and Lenz's Law - square coil

1. Feb 10, 2015

### cseil

1. The problem statement, all variables and given/known data
A square coil rotates around an axis passing through the center. It is inside a magnetic field of B= 0.6T uniform and constant. The side of the coil is a = 2cm, the resistance R is 0.1 ohm.

The coil is powered by a generator that gives an emf = 0.2 + 0.24sin(ωt).
The current during the motion of the coil is constant. Calculate i and ω.

3. The attempt at a solution

The induced emf is $\epsilon_i = Ba^2\omega sin(\omega t)$.

I can't understand how to go on with the problem. I cannot understand why the current stays constant if both the intial emf and the induced emf changes as sin(ωt).

Could you help me please?
Thank you

2. Feb 10, 2015

### lightgrav

the total emf is part from the generator (given) and part from being induced.
For the current to be constant, these need to add to a constant emf (ie, be 180 deg out-of-phase) 0.2V.
So, given its (ohmic) Resistance, what is I ?