The point charges $Q$ and $-2Q$ are placed at some distance apart. If the electric field at the location of $Q$ is $\vec E$  , then the electric field at the location of $-2Q$ will be :

Whose result the whole electrostatic is ?

Three charged particle $A, B$ and $C$ with charges $-4 q,  2 q$ and $-2 q$ are present on the circumference of a circle of radius $d$. the charged particles $A, C$ and centre $O$ of the circle formed an equilateral triangle as shown in figure. Electric field at $O$ along $x-$direction is

A point charge of $10\,\mu C$ is placed at the origin. At what location on the $X$-axis should a point charge of $40\,\mu\,C$ be placed so that the net electric field is zero at $x =2\,cm$ on the $X$-axis ?

In the given figure distance of the point from $A$ where the electric field is zero is......$cm$

Four charges $q, 2q, -4q$ and $2q$ are placed in order at the four corners of a square of side $b$. The net field at the centre of the square is