Find ratio of electric field at point $A$ and $B.$ Infinitely long uniformly charged wire with  linear charge density $\lambda$ is kept along $z-$ axis

Two point charges $q_1$ and $q_2 (=q_1/2)$ are placed at points $A(0, 1)$ and $B(1, 0)$ as shown in the figure. The electric field vector at point $P(1, 1)$ makes an angle $\theta $ with the $x-$ axis, then the angle $\theta$ is

A wire of length $L\, (=20\, cm)$, is bent into a semicircular arc. If the two equal halves of the arc were each to be uniformly charged with charges $ \pm Q\,,\,\left[ {\left| Q \right| = {{10}^3}{\varepsilon _0}} \right]$ Coulomb where $\varepsilon _0$ is the permittivity (in $SI\, units$) of free space] the net electric field at the centre $O$ of the semicircular arc would be

Explain electric field and also electric field by point charge.

The intensity of electric field required to balance a proton of mass $1.7 \times {10^{ - 27}} kg$ and charge $1.6 \times {10^{ - 19}} C$ is nearly

The distance between the two charges $25\,\mu C$ and $36\,\mu C$ is $11\,cm$ At what point on the line joining the two, the intensity will be zero