I appreciate the link to the field strength calculator. http://www.calctool.org/CALC/phys/electromagnetism/solenoid I'm also looking for recommendations on sources for magnets. What I'm trying to do is put together a Faraday Rotation Effect Lab. This is my Faraday Rotator, a 12 cm x 2.0 cm cylinder of something close to flint glass with a half decent Verdet Constant. Does anyone have pointers to a lab supply company with solenoids capable of 0.5T or higher?