How is hall voltage ΔV = Ed derived?

[Turion]

Derivation: http://s24.postimg.org/nhiqgg4qt/untitled.png

How did they get ΔV=Ed? (d=width of the conductor)

Sorry, I'm really rusty on my physics. Finding it quite difficult to review.

 

[rock.freak667]

Electric field strength can be defined as E = V/d.

See here for more information.