Three point charges $q,-2 q$ and $2 q$ are placed on $x$-axis at a distance $x=0, x=\frac{3}{4} R$ and $x=R$ respectively from origin as shown. If $q =2 \times 10^{-6}\,C$ and $R =2\,cm$, the magnitude of net force experienced by the charge $-2 q$ is .......... $N$
$5442$
$5440$
$5448$
$5475$
A cube of side $b$ has a charge $q$ at each of its vertices. The electric field due to this charge distribution at the centre of this cube will be
A charge ${q_1}$ exerts some force on a second charge ${q_2}$. If third charge ${q_3}$ is brought near, the force of ${q_1}$ exerted on ${q_2}$
There are two charges $+1$ microcoulombs and $+5$ microcoulombs. The ratio of the forces acting on them will be
Two positive point charges of unequal magnitude are placed at a certain distance apart. A small positive test charge is placed at null point, then
Two identical charged spheres are suspended by strings of equal lengths. The strings make an angle of $30^o$ with each other. When suspended in a liquid of density $1\, g\, cm^{-3}$, the angle remains the same. If density of the material of the sphere is $4/3\, g\, cm^{-3}$, the dielectric constant of the liquid is