1. The problem statement, all variables and given/known data Two metal bars, 1 and 2, are identical in all ways, except that bar 2 has twice the width of 1. The bars are parallel to each other, but far apart from each other, in a uniform magnetic field and carry the same amount of current in a direction perpendicular to the field. How does the Hall voltage of bar 2 compare to that of bar 1? 2. Relevant equations The equation for Hall effect is nq=(-JB/E). I know that I can relate E to V by using E=(V/d). 3. The attempt at a solution If the width of bar 2 is twice the with of bar 1, then (because of E=V/d) the voltage of 2 would be two times greater than bar 1. I'm confused about why I need to use the Hall effect if I can just use E=V/d.