I see that I made two mistakes (hopefully that's it!). One when calculating vf and one when calculating B.
Correcting, this gives me:
v_{f} = 4.4 \sqrt{H} \frac{m}{s}
B = \sqrt{\frac{MgR}{(4.4\sqrt{H})s^2}}
Is that better?
Homework Statement
"Consider a square metal picture frame of side length s, mass M, and total electrical resistance R. It is dropped from rest from a height H above a region of uniform magnetic field pointing into the page. The frame accelerates downward under the influence of gravity until...