Assertion : A charged particle free to move in an electric field always move along an electric line of force.

Reason : The electric line of force diverge from a positive charge and converge at a negative charge.

Assertion : An applied electric field will polarize the polar dielectric material.

Reason : In polar dielectrics, each molecule has a permanent dipole moment but these are randomly oriented in the absence of an externally applied electric field.

Assertion: Gravitational force between nucleus and electron in an atom is negligible to the electrical force.

Reason: The electrical force is experienced by charged particles only.

Four electric charges $+q, +q, -q$ and $-q$ are placed at the corners of a square of side $2L.$ The electric potential at point $A,$ midway between the two charges $+q$ and $+q,$ is

The electric potential $\mathrm{V}$ at any point $(\mathrm{x}, \mathrm{y}, \mathrm{z}),$ all in meters in space is given by $\mathrm{V}=4{\mathrm{x}}^2$ volt. The electric field at the point $(1,0,2)$ in volt/meter is

Three changes, each $+q$, are placed at the corners of an isosceles triangle $ABC$ of sides $BC$ and $AC$, $2a$. $D$ and $E$ are the mid-points of $BC$ and $CA$. The work done in taking a charge $Q$ from $D$ to $E$ is