Two point charges $4\,\mu C$ and $ – 1\,\mu C$ are kept at a distance of $3\ m$ from each other. What is the electric potential at the point where the electric field is zero?……$V$

A conducting sphere of radius $R$ is given a charge $Q$. The electric potential and the electric field at the centre of the sphere respectively are

The radius of a charged metal sphere $(R)$ is $10\,cm$ and its potential is $300\,V$. Find the charge density on the surface of the sphere

Two charges of $4\,\mu C$ each are placed at the corners $A$ and $B $ of an equilateral triangle of side length $0.2\, m $ in air. The electric potential at $C$ is $\left[ {\frac{1}{{4\pi {\varepsilon _0}}} = 9 \times {{10}^9}\,\frac{{N{\rm{ – }}{m^2}}}{{{C^2}}}} \right]$

A charge $ + q$ is fixed at each of the points $x = {x_0},\,x = 3{x_0},\,x = 5{x_0}$….. $\infty$, on the $x – $axis and a charge $ – q$ is fixed at each of the points $x = 2{x_0},\,x = 4{x_0},x = 6{x_0}$,….. $\infty$. Here ${x_0}$ is a positive constant. Take the electric potential at a point due to a charge $Q$ at a distance $r$ from it to be $Q/(4\pi {\varepsilon _0}r)$. Then, the potential at the origin due to the above system of charges is