Figure shows two conducting thin concentric shells of radii r and 3 r . The outer shell carries charge q . Inner shell is neutral. Find the charge that will flow from inner shell to earth after the switch S is closed.

Question

Figure shows two conducting thin concentric shells of radii r and 3 r . The outer shell carries charge q . Inner shell is neutral. Find the charge that will flow from inner shell to earth after the switch S is closed. <img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/bad91e20a739a08a903705f78dfb8dd2-.png" /> (A) -(q/3) (B) +(q/2) (C) -(q/2) (D) +(q/3)

Tardigrade Admin · Accepted Answer

Let q1 be the final charge on inner shell. So, potential of inner shell must be zero ( Kq /3 r )+ ( Kq 1/ r )=0 ⇒ q 1=(- q /3) so (q/3) charge from shell must flow towards earth.

Q. Figure shows two conducting thin concentric shells of radii $r$ and $3 r .$ The outer shell carries charge $q .$ Inner shell is neutral. Find the charge that will flow from inner shell to earth after the switch $S$ is closed.

$- \frac{q}{3}$

$+ \frac{q}{2}$

$- \frac{q}{2}$

$+ \frac{q}{3}$

Let $q_{1}$ be the final charge on inner shell.
So, potential of inner shell must be zero
$\frac{K q}{3 r} + \frac{K q _{1}}{r} = 0$
$\Rightarrow q_{1} = \frac{- q}{3}$
so $\frac{q}{3}$ charge from shell must flow towards earth.

Q. Figure shows two conducting thin concentric shells of radii r and 3r. The outer shell carries charge q. Inner shell is neutral. Find the charge that will flow from inner shell to earth after the switch S is closed.

−3q​

+2q​

−2q​

+3q​