Assertion: $A$ metallic shield in the form of a hollow shell may be built to block an electric field.
Reason: In a hollow spherical shield,the electric field inside it is zero at every point.

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

If two conducting spheres are separately charged and then brought in contact,which of the following statements is true?

Is the induced charge on the surface of a metal or inside it?

Three identical uncharged metal spheres are at the vertices of an equilateral triangle. One at a time,a small sphere is connected by a conducting wire with a large metal sphere that is charged. The center of the large sphere is on the straight line perpendicular to the plane of the equilateral triangle and passing through its center (see figure). As a result,the first small sphere acquires charge $q_1$ and the second acquires charge $q_2$ $(q_2 < q_1)$. The charge that the third sphere $q_3$ will acquire is (Assume $l >> R$,$l >> r$,$d >> R$,$d >> r$):

Two metal spheres of radius $R$ and $3R$ have the same surface charge density $\sigma$. If they are brought in contact and then separated,the surface charge density on the smaller and bigger sphere becomes $\sigma_1$ and $\sigma_2$,respectively. The ratio $\frac{\sigma_1}{\sigma_2}$ is: