When the distance between the charged particles is halved,the force between them becomes

$A$ charge $Q$ is distributed over a line of length $L$. Another point charge $q$ is placed at a distance $r$ from the centre of the line distribution. Then the force experienced by $q$ is

The force between two point charges $A$ and $B$ is $F$. If $75\%$ of the charge on $A$ is transferred to $B$,then the new force between $A$ and $B$ is:

Two pith balls,each carrying charge $+q$,are hung from a hook by two strings of length $L$. It is found that when each charge is tripled,the angle between the strings doubles. What was the initial angle between the strings (in $^{\circ}$)?

$A$ charged particle of mass $m_{1}$ and charge $q_{1}$ is revolving in a circle of radius $r$. Another charged particle of charge $q_{2}$ and mass $m_{2}$ is situated at the centre of the circle. If the velocity and time period of the revolving particle are $v$ and $T$ respectively,then:

Two point charges $+3\,\mu C$ and $+8\,\mu C$ repel each other with a force of $40\,N$. If a charge of $-5\,\mu C$ is added to each of them,then the force between them will become....$N$