An infinite long line charge of charge per unit length $\lambda$ is passing one of the edge of a cube. Length of edge of the cube is $l$. (see figure)

Four point charges $q_A=2 \mu C, q_B=-5 \mu C, q_C=2 \mu C, q_D=-5 \mu C$ are located at the corners of a square $ABCD$ of side $10 \mathrm{cm}.$ The force acting on a charge of $1 \mu \mathrm{C}$ placed at centre of the square is

A uniformly charged solid sphere of radius R has potential $V_0$ (measured with respect to $\infty$ ) on its surface. For this sphere the equipotential surfaces with potential $\frac{3V_0}{2},\frac{5V_0}{4},\frac{3V_0}{4}$ and $\frac{V_0}{4}$ have radius $R_1$ , $R_2, R_3$ and $R_4$ respectively. Then

Note : This question had two option correct at the time of examination. Proper corrections are made in the question to avoid it.

Three charges are placed at the three vertices of an equilateral triangle of side $a$ as shown in the figure. The force experienced by the charge placed at the vertex $A$ in a direction normal to $BC$ is

An infinite number of point charges, each carrying $1 \mu \mathrm{C}$ charge, are placed along the y-axis at $y=1 \mathrm{m},2 \mathrm{m},4 \mathrm{m},8 \mathrm{m} ... .$

The total force on a $1 \mathrm{C}$ point charge, placed at the origin, is $x\times {10}^3 \mathrm{N}$. The value of $x$, to the nearest integer, is ___ .

[Take $\frac{1}{4\pi {ϵ}_0}=9\times {10}^9 \mathrm{N} {\mathrm{m}}^2 {\mathrm{C}}^{-2}$]

Shown in the figure is a shell made of a conductor. It has inner radius $a$ and outer radius $b$, and carries charge $Q$ . At its centre a dipole $\overrightarrow{\mathit{p}}$ is placed as shown then:

Eleven equal point charges, all of them having a charge $+Q,$ are placed at all the hour positions of a circular clock of radius $r$ except at the $10 \mathrm{h}$ position. What is the electric field strength at the centre of the clock?