E-field of a moving charge at constant velocity

[STosh9]

I came upon this page that provides the answer:
http://farside.ph.utexas.edu/teaching/em/lectures/node125.html

But I can't figure out what gamma(u) is. Could anyone help?

 

[Doc Al]

But I can't figure out what gamma(u) is.

That's the usual Lorentz factor of special relativity. See: Lorentz factor

 

[STosh9]

Thanks. So if the charge is moving slow compared to c, then the field resembles that of a stationary charge.