Drag At Light Speed

A particle in B orbit does not accelerate indefinitely,

\(\pi q c B=\pi q E=Ac^2\)

where \(c\) is light speed and \(Ac^2\) is drag of free space at light speed.  So,

\(A=\cfrac{\pi qB}{c}=\cfrac{\pi qE}{c^2}\)

At last, a simple expression for the drag factor \(A\).