Three charged concentric nonconducting shells are given as shown in the figure. Find the potential at point $A$.

An imaginary equilateral triangle $ABC$ of side length $2 \ m$ is placed in a uniform electric field $\vec{E} = 10 \ N \ C^{-1}$ as shown. Then,$V_A - V_B =$

Three charges each of value $+q$ are placed at the corners of an isosceles triangle $ABC$ with sides $AB = AC = 2a$. The midpoints of $AB$ and $AC$ are $D$ and $E$ respectively. The work done in taking a charge $Q$ from $D$ to $E$ is (where $\varepsilon_0$ is the permittivity of free space):

The electric potential at the surface of a hollow metallic sphere is $10\, V$. What will be the electric potential at its center (in $V$)?

Two electric charges of $9 \mu C$ and $-3 \mu C$ are placed $0.16 \ m$ apart in air. There will be a point $P$ on the line joining the two charges and between them where the electric potential is zero. The distance of $P$ from the $9 \mu C$ charge is: (in $m$)

Two charged spheres of radii $R_1$ and $R_2$ have equal surface charge density. The ratio of their potential is