Consider a metal sphere of radius $R$ that is cut in two parts along a plane whose minimum distance from the sphere's centre is $h$. Sphere is uniformly charged by a total electric charge $Q$. The minimum force necessary to hold the two parts of the sphere together, is
$\frac{{{Q^2}\left( {{R^2} - {h^2}} \right)}}{{4\pi \,{ \in _0}\,{R^4}}}$
$\frac{{{Q^2}}}{{4\pi \,{ \in _0}\,{R^2}}}$
$\frac{{{Q^2}\left( {R - h} \right)}}{{32\pi \,{ \in _0}\,{R^3}}}$
$\frac{{{Q^2}\left( {{R^2} - {h^2}} \right)}}{{32\pi \,{ \in _0}\,{R^4}}}$
Consider a uniform spherical volume charge distribution of radius $R$. Which of the following graphs correctly represents the magnitude of the electric field $E$ at a distance $r$ from the centre of the sphere?
Two infinitely long parallel conducting plates having surface charge densities $ + \sigma $ and $ - \sigma $ respectively, are separated by a small distance. The medium between the plates is vacuum. If ${\varepsilon _0}$ is the dielectric permittivity of vacuum, then the electric field in the region between the plates is
The electric field due to a uniformly charged sphere of radius $R$ as a function of the distance $r$ from its centre is represented graphically by
A positive charge $q$ is placed in a spherical cavity made in a positively charged sphere. The centres of sphere and cavity are displaced by a small distance $\vec l $ . Force on charge $q$ is :
Three infinitely long charged thin sheets are placed as shown in figure. The magnitude of electric field at the point $P$ is $\frac{x \sigma}{\epsilon_0}$. The value of $x$ is_____. (all quantities are measured in $SI$ units).