The equation of an equipotential line in an electric field is $y = 2x$, then the electric field strength vector at $(1, 2)$ may be
$4 \hat i+ 3 \hat j$
$4 \hat i + 8 \hat j$
$8 \hat i + 4 \hat j$
$- 8 \hat i + 4 \hat j$
Draw an equipotential surface for an uniform electric field.
The diagrams below show regions of equipotentials.A positive charge is moved from $A$ to $B$ in each diagram.
Draw an equipotential surface for a point charge.
The angle between the electric lines of force and the equipotential surface is
Two point charges of magnitude $+q$ and $-q$ are placed at $\left( { - \frac{d}{2},0,0} \right)$ and $\left( {\frac{d}{2},0,0} \right)$, respectively. Find the equation of the equipotential surface where the potential is zero.