Consider a metal ball of radius $r$ moving at a constant velocity $v$ in a uniform magnetic field of induction $\vec{B}$. Assuming that the direction of velocity forms an angle $\alpha$ with the direction of $\vec{B}$,the maximum potential difference between points on the ball is

• A
  $r|\vec{B}||\vec{v}| \sin \alpha$
• B
  $|\vec{B}||\vec{v}| \sin \alpha$
• C
  $2r|\vec{B}||\vec{v}| \sin \alpha$
• D
  $2r|\vec{B}||\vec{v}| \cos \alpha$