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

Charge is uniformly distributed on the surface of a hollow hemisphere. Let $O$ and $A$ be two points on the base of the hemisphere and $V_0$ and $V_A$ be the electric potentials at $O$ and $A$ respectively. Then,

Charges of $ + \frac{{10}}{3} \times {10^{ - 9}}C$ are placed at each of the four corners of a square of side $8\,cm$. The potential at the intersection of the diagonals is

Which of the following statements is true about the flow of electrons in an electric circuit?

A solid conducting sphere having a charge $Q$ is surrounded by an uncharged concentric conducting hollow spherical shell. Let the potential difference between the surface of the solid sphere and that of the outer surface of the hollow shell be $V$. If the shell is now given a charge of $-3Q$, the new potential difference between the same two surfaces is......$V$

Two tiny spheres carrying charges $1.5 \;\mu\, C$ and $2.5\; \mu\, C$ are located $30 \;cm$ apart. Find the potential and electric field

$(a)$ at the mid-point of the line joining the two charges, and

$(b)$ at a point $10\; cm$ from this midpoint in a plane normal to the line and passing through the mid-point.