Two charged conducting spheres of radii $5 \ cm$ and $10 \ cm$ have equal surface charge densities. If the electric field on the surface of the smaller sphere is $E$,then the electric field on the surface of the larger sphere is

Two point charges $-q$ and $+q/2$ are situated at the origin $(0, 0, 0)$ and at the point $(a, 0, 0)$ respectively. The point along the $X$-axis where the electric field vanishes is:

Charge $Q$ is distributed non-uniformly over a ring of radius $R$. $P$ is a point on the axis of the ring at a distance $3R$ from its centre. Which of the following is a wrong statement?

Two charges $+Q$ and $-2 Q$ are located at points $A$ and $B$ on a horizontal line as shown below. The electric field is zero at a point which is located at a finite distance:

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

Two electric charges $9e$ and $3e$ are placed at a distance $r$ from each other. The point where the electric field intensity is zero is at a distance of .......