A unit positive point charge of mass $m$ is projected with a velocity $V$ inside the tunnel as shown. The tunnel has been made inside a uniformly charged non conducting sphere. The minimum velocity with which the point charge should be projected such it can it reach the opposite end of the tunnel, is equal to
$[\rho R^2/4m\varepsilon_0]^{1/2}$
$[\rho R^2/24m\varepsilon_0]^{1/2}$
$[\rho R^2/6m\varepsilon_0]^{1/2}$
zero because the initial and the final points are at same potential.
Consider the configuration of a system of four charges each of value $+q$ . The work done by external agent in changing the configuration of the system from figure $(1)$ to figure $(2)$ is
Two charges $-q$ each are separated by distance $2d$. A third charge $+ q$ is kept at mid point $O$. Find potential energy of $+ q$ as a function of small distance $x$ from $O$ due to $-q$ charges. Sketch $P.E.$ $v/s$ $x$ and convince yourself that the charge at $O$ is in an unstable equilibrium.
If an electron moves from rest from a point at which potential is $50\, volt$ to another point at which potential is $70\, volt$, then its kinetic energy in the final state will be
Two points $P$ and $Q$ are maintained at the potentials of $10\ V$ and $- 4\ V$, respectively. The work done in moving $100$ electrons from $P$ to $Q$ is
When three electric dipoles are near each other, they each experience the electric field of the other two, and the three dipole system has a certain potential energy. Figure below shows three arrangements $(1)$ , $(2)$ and $(3)$ in which three electric dipoles are side by side. All three dipoles have the same magnitude of electric dipole moment, and the spacings between adjacent dipoles are identical. If $U_1$ , $U_2$ and $U_3$ are potential energies of the arrangements $(1)$ , $(2)$ and $(3)$ respectively then