A planetary magnetosphere has a dipole magnetic field with a dipole moment M. The dipole axis is aligned along the rotational axis of the planet. All of the plasma in the magnetosphere rotates with the planet at an angular velocity . Using spherical (r. 8. 4) coordinates derive equations for the following. (a) (b) (c) (d) The magnetic field. B. The Ex B drift velocity. V = * 7. The electric field . The electrostatic potential, 0, such that E-VO.