Two charged conducting spheres of radii $a$ and $b$ are connected to each other by a conducting wire. The ratio of charges of the two spheres respectively is:

Two conducting spheres of radii $20\, cm$ and $15\, cm$ are placed on insulating stands. Both are given an equal charge of $10\ \mu C$. When they are connected by a copper wire and then disconnected,which of the following is true?

$A$ metal cube is given a positive charge $(+Q)$. Which of the following statements is true?

Explain the electrostatics of conductors. Explain the effects produced inside a metallic conductor placed in an external electric field.

$A$ spherical metal shell $A$ of radius $R_A$ and a solid metal sphere $B$ of radius $R_B < R_A$ are kept far apart and each is given charge $+Q$. Now they are connected by a thin metal wire. Then:
$(A)$ $E_A^{\text{inside}} = 0$
$(B)$ $Q_A > Q_B$
$(C)$ $\frac{\sigma_A}{\sigma_B} = \frac{R_B}{R_A}$
$(D)$ $E_A^{\text{on surface}} < E_B^{\text{on surface}}$

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: