Thanks for the speedy response. How about when the magnetic field strength is increased to a huge amount whilst the current remains low?
Power = current * voltage = I V
I= Force/(magnetic field * arc length)
Warrington's formula for still air: V=28740*arc length/I^0.4
As current reduces, voltage increases less. Therefore increasing the magnetic field would reduce power asymptotically? Is the still air formula creating the problem here??