Answer
The potential difference is $~~1.20~V$
Work Step by Step
The magnetic field is in the +y direction.
By the right hand rule, as the solid moves in the +x direction, there is a force on the electrons that pushes them in the -z direction.
The potential difference is $V = vBd_z$
We can find the potential difference:
$V = vBd_z$
$V = (20.0~m/s)(30.0~mT)(2.00~m)$
$V = 1.20~V$
The potential difference is $~~1.20~V$.
