A ring of radius $R$ is charged uniformly with a charge $+\,Q$ . The electric field at a point on its axis at a distance $r$ from any point on the ring will be
$\frac{{KQ}}{{({r^2} - {R^2})}}$
$\frac{{KQ}}{{{r^2}}}$
$\frac{{KQ}}{{{r^3}}}{({r^2} - {R^2})^{1/2}}$
$\frac{{KQr}}{{{R^3}}}$
A uniformly charged rod of length $4\,m$ and linear charge density $\lambda = 30\,\mu C/m$ is placed as shown in figure. Calculate the $x-$ component of electric field at point $P$.
How many electrons should be removed from a coin of mas $1.6 \,g$, so that it may float in an electric field of intensity $10^9 \,N / C$ directed upward?
Four charges $q, 2q, -4q$ and $2q$ are placed in order at the four corners of a square of side $b$. The net field at the centre of the square is
Explain electric field and also electric field by point charge.
Select the correct statement : (Only force on a particle is due to electric field)