If the potential function is define as
$V=(-3x+4y+12z)V,$
then magnitude of electric field $E(x, y, z)$ is

From the following graph, find the value of $\left|\overrightarrow{E}\right|$ at $r=3.5 \mathrm{m}$

If the given figure shows equipotential surfaces, then the magnitude of electric field is

A uniform electric field of $200 {\mathrm{Vm}}^{-1}$ is directed at $45°$ with $x-$axis as shown in figure. The co-ordinates of point $P$and point $Q$ are $(1, 0)$ and $(0, 2).$ Find the potential difference, $V_P-V_Q$ (in volts).