Two identical balls having like charges and placed at a certain distance apart repel each other with a certain force. They are brought in contact and then moved apart to distance equal to half their initial separation. The force of repulsion between them increases $4.5\,times$ in comparison with the initial value. The ratio of the initial charges of the balls is

Two conducting spheres of radii $r_1$ and $r_2$ have same electric fields near their surfaces. The ratio of their electric potentials is

A charged object is launched inside a time varying electric field. Its motion is recorded by a video camera on a video tape. When it is at a certain moment $A$ , its position vector $\vec r$, velocity $\vec v$ and acceleration $\vec a$ are measured. A student watches the video at a later time but mistakenly plays the tape in the reverse direction. What is the position, velocity, and acceleration of the object, at moment $A$ observed by the student respectively?

In the given circuit if point $C$ is connected to the earth and a potential of $+2000\,V$ is given to the point $A$ , the potential of $B$ is…..$V$

The electric potential $(V)$ as a function of distance $(x)$ [in meters] is given by $V = (5x^2 + 10 x -9)\, Volt$. The value of electric field at $x = 1\, m$ would be……$Volt/m$