4. m•v² / r = q•B•v
Make sense? Well, at least the units work out so far and I think I'm on the right track.
Just a side note here. Dividing both sides by v and m gives:
5. v / r = q•B / m
Note that since q, B, and m are known without regard to the velocity v the right side represents a constant. So v/r must always be a constant under these circumstances and it follows that if v increases, so must r in just the same proportion.
Anyway, moving on and solving (5) for r and substituting in (3) for v we get:
6. r = m•v / q•B = (1/B) • √[ 2•V•m / q ]
Which gives:
(1/1.6 tesla) • √[ ( 2 • 10x10³ volts • 3.3x10^-27 kg ) / ( 1.6x10^-19 Coulomb ) ]
or 1.269381 centimeters
So about 1.27cm is what I get.