CBSE Class 12 · 2020 · ElectrostaticsMultiple Choice

Assertion (A): Equal amounts of positive and negative charges are distributed uniformly on two halves of a thin circular ring as shown in the figure. The resultant electric field at the centre O of the ring is along OC. Reason (R): It is so because the net potential at O is not z …

Four point charges of $1\mu \text{C}$, $-2\mu \text{C}$, $1\mu \text{C}$ and $-2\mu \text{C}$ are placed at the corners A, B, C and D respectively of a square of side 30 cm. Find the net force acting on a charge of $4\mu \text{C}$ placed at the centre of the square.

Three point charges $1\text{pC}$ each are kept at the vertices of an equilateral triangle of side 10 cm. Find the net electric field at the centroid of the triangle.

(a)(i) Draw equipotential surfaces for an electric dipole. (ii) Two point charges $q_1$ and $q_2$ are located at ${\vec{r}}_1$ and ${\vec{r}}_2$ respectively in an external electric field $\vec{E}$. Obtain an expression for the potential energy of the system. (iii) The dipole moment …

(b)(i) A thin spherical shell of radius $R$ has a uniform surface charge density $\sigma$. Using Gauss's law, deduce an expression for the electric field (i) outside and (ii) inside the shell. (ii) Two long straight thin wires AB and CD have linear charge densities …

The magnitude of the electric field due to a point charge object at a distance of 4.0 m is 9 N/C. From the same charged object the electric field of magnitude 16 N/C will be at a distance of