Electromagnetic Magic: The Relativistically Rotating Disk
  A closed form analytic solution is found for the electromagnetic field of the charged uniformly rotating conducting disk for all values of the tip speed $v$ up to $c$. For $v=c$ it becomes the Magic field of the Kerr-Newman black hole with $G$ set to zero.   The field energy, field angular momentum and gyromagnetic ratio are calculated and compared with those of the electron.   A new mathematical expression that sums products of 3 Legendre functions each of a different argument, is demonstrated. 
D. Lynden-Bell