$F_g$ and $F_e$ represent the gravitational and electrostatic forces,respectively,between two electrons situated at a distance of $10 \ cm$. The ratio of $F_g/F_e$ is of the order of:

Five balls numbered $1$ to $5$ are suspended using separate threads. Pairs $(1,2), (2,4)$ and $(4,1)$ show electrostatic attraction while pairs $(2,3)$ and $(4,5)$ show repulsion. Therefore,ball $1$ must be:

The unit of electric field is not equivalent to

Three point charges $q_1, q_2, q_3$ are placed at the vertices of a triangle. If the forces on $q_1$ and $q_2$ are $(2\hat{i} - \hat{j}) \, N$ and $(\hat{i} + 3\hat{j}) \, N$,respectively,then what will be the force on $q_3$?

Two small spheres of each charge $q$,mass $m$ and material density $d$ are suspended from a fixed point with the help of inextensible light threads. When the spheres are in air,the angle between the threads is $90^{\circ}$. When the spheres are suspended in a liquid of density $\frac{2}{3} d$,the angle between the threads is $60^{\circ}$. The value of the dielectric constant of the liquid is

Two equal negative charges $-q$ are fixed at the points $(0, a)$ and $(0, -a)$ on the $Y$-axis. $A$ positive charge $Q$ is released from rest at the point $(2a, 0)$ on the $X$-axis. The charge $Q$ will: