The charges $2q, -q, -q$ are located at the vertices of an equilateral triangle. At the center of the triangle:

$A$ ring of radius $R$ is charged uniformly with a charge $+Q$. The electric field at a point on its axis at a distance $r$ from any point on the ring will be

The potential in an electric field varies as $V = (x^2 - y^2)$. The electric lines of force in the $X-Y$ plane are

Four point charges $-q, +q, +q$ and $-q$ are placed on the $y$-axis at $y = -2d, y = -d, y = +d$ and $y = +2d$,respectively. The magnitude of the electric field $E$ at a point on the $x$-axis at $x = D$,with $D >> d$,will vary as:

Electric field at a distance $r$ from an infinitely long uniformly charged straight conductor,having linear charge density $\lambda$ is $E_1$. Another uniformly charged conductor having same linear charge density $\lambda$ is bent into a semicircle of radius $r$. The electric field at its centre is $E_2$. Then

Point charges $+8q$ and $-2q$ are placed at $x = 0$ and $x = L$ respectively. At which point on the $X$-axis will the resultant electric field intensity be zero?