Two conductors of the same shape and size,one of copper and the other of aluminium (which is less conducting),are placed in a uniform electric field. What can be said about the charge induced in the aluminium conductor?

Two concentric spherical shells of radius $R_1$ and $R_2$ have $q_1$ and $q_2$ charge respectively as shown in the figure. How much charge will flow through key $k$ when it is closed?

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:

$A$ small conducting sphere is hung by an insulating thread between the plates of a parallel plate capacitor as shown in the figure. The net force on the sphere is

Two metallic concentric shells are shown. Before closing the switch,the charge on the inner shell is $Q$ and the charge on the outer shell is $2Q$. The potential at point $A$ is $V$. What will be the potential at the same point after closing the switch?

$A$ point charge of magnitude $+ 1\,\mu C$ is fixed at $(0, 0, 0)$. An isolated uncharged spherical conductor is fixed with its center at $(4, 0, 0)$. The potential and the induced electric field at the center of the sphere are: