Define an electrostatic potential energy.

Assertion : Electric potential and electric potential energy are different quantities.

Reason : For a system of positive test charge and point charge electric potential energy $=$ electric potential.

Three charges $Q, +q$ and $+q$ are placed at the vertices of a right -angle isosceles triangle as shown below. The net electrostatic energy of the configuration is zero, if the value of $Q$ is

In Millikan's experiment, an oil drop having charge $q$ gets stationary on applying a potential difference $V$ in between two plates separated by a distance $d$. The weight of the drop is

A charged particle of charge $Q $ is held fixed and another charged particle of mass $m$ and charge $q$ (of the same sign) is released from a distance $r.$ The impulse of the force exerted by the external agent on the fixed charge by the time distance between $Q$ and $q$ becomes $2r$ is

Mass of charge $Q$ is $m$ and mass of charge $2Q$ is $4\,m$ . If both are released from rest, then what will be $K.E.$ of $Q$ at infinite separation