Hall Effect$--$ A metal strip $6\mathrm{.}50-cm$ long, $0\mathrm{.}880-cm$ wide, and $0\mathrm{.}760-mm$ thick moves with constant velocity, magnitude $v$ along positive $y-$axis, through a magnetic field, $B=1\mathrm{.}20-mT$ along positive $z-$axis. As equilibrium is achieved potential difference of $3\mathrm{.}90{10}^{-6}-V$ is measured between points $x_1$ and $x_2($as shown below$).$ Determine the magnitude of the velocity, $v.$