The electric potential in a region is given by $V=2 x y-3 z x+5 y^{2}$, with $V$ in volts and the coordinates in meters. Find (a) the potential and (b) the components of the electric field at the point $x=3 \mathrm{~m}$, $y=3 \mathrm{~m}, z=1 \mathrm{~m}$.