Two charges 14 $$\mu$$C and $$-$$4 $$\mu$$C are placed at ($$-$$12 cm, 0, 0) and (12 cm, 0, 0) in an external electric field $$E = \left( {{B \over {{r^2}}}} \right)$$, where B = 1.2 $$\times$$ 10⁶ N/(cm²) and r is in metres. The electrostatic potential energy of the configuration is

Assertion (A) : A negative charge in an electric field moves along the direction of the electric field.

Reason (R) : On a negative charge a force acts in the direction of the electric field.

Equipotentials at a large distance from a collection of charges whose total sum is not zero are -

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