# Homework Help: Griffiths 7.45

1. Apr 25, 2008

### ehrenfest

1. The problem statement, all variables and given/known data
A perfectly conducting spherical shell of radius 'a' rotates about the z-axis with angular velocity $\omega$ in a uniform magnetic field $\mathbf{B} = B_0 \hat{\mathbf{z}}$. Calculate the emf developed between the "north pole" and the equator.

2. Relevant equations

3. The attempt at a solution
I don't understand how emf makes sense in this context. I have only seen emf in currents. The emf is defined as an integral around a LOOP:
$$\int_{loop} \mathbf{f} \cdot d\mathbf{l}$$
I don't see how you would generalize it here.