Two point charges of $5 \mathrm{\mu C}$ and $-2 \mathrm{\mu C}$ are kept at the opposite corners $A$ and $C$ of a square respectively. The potential difference between the other corners of the square will be

A capacitor of $4\mu F$ is connected, as shown in the circuit below, internal resistance of the battery is $0.5 \Omega$. The amount of charge on the capacitor plates will be?

Three-point charges $q, 2q$ and $8q$ are to be placed on a $9 \mathrm{cm}$ long straight line. Find the separation between $q$ and $2q$ where the charges should be placed such that the potential energy of this system is minimum.

Three charges are placed at the vertices of a right-angled triangle (isosceles triangle) as shown below. The net potential energy of the system is,

What is the electric potential due to point charge of $3 nC$ at a distance of $9 cm$?

A parallel plate capacitor is made of two dielectric blocks in a series. One of the blocks has thickness $d_1$ and dielectric constant $k_1$, and the other has thickness $d_2$ and dielectric constant $k_2$ as shown In the figure below, this arrangement can be thought of as a dielectric slab of thickness $(d=d_1+d_2)$ and effective dielectric constant $k$. Then $k$ is