$A$ conducting sphere of radius $10\, cm$ is charged with $10\,\mu C$. Another uncharged sphere of radius $20\, cm$ is allowed to touch it for some time. After the spheres are separated,the ratio of the surface charge densities on the spheres will be:

Which of the following statements is $NOT$ true for a charged conducting sphere?

Which of the following statements are correct?
$A$. Inside the conductor, the electrostatic field is zero.
$B$. Electric field at the surface of a charged conductor does not depend on its surface charge density.
$C$. The interior of a charged conductor can have no excess charge in the static situation.
$D$. At the surface of a charged conductor, the electrostatic field must be normal to the surface at every point.
$E$. The electrostatic potential is zero everywhere inside a charged conductor.
Choose the correct answer from the options given below:

The figure shows a solid conducting sphere of radius $1 \, m$,enclosed by a metallic shell of radius $3 \, m$ such that their centers coincide. If the outer shell is given a charge of $6 \, \mu C$ and the inner sphere is earthed,find the charge on the surface of the inner sphere in $\mu C$.

Two spheres of radius $R$ and $2R$ having charge $Q$ and $2Q$ respectively are placed far away from each other. How much charge will flow when key $k$ is pressed?

For the situation shown in the figure,mark the correct statement. $A$ point charge $q$ is placed at a distance $d$ from the surface of a neutral hollow conductor of radius $R$.