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

Two point charges $( + Q)$ and $( - 2Q)$ are fixed on the $X-$axis at positions $a$ and $2a$ from origin respectively. At what positions on the axis, the resultant electric field is zero

A uniformly charged rod of length $4\,m$ and linear charge density $\lambda  = 30\,\mu C/m$ is placed as shown in figure. Calculate the $x-$ component of electric field at point $P$.

The bob of a simple pendulum has mass $2\,g$ and a charge of $5.0\,\mu C$. It is at rest in a uniform horizontal electric field of intensity $2000\,\frac{V}{m}$. At equilibrium, the angle that the pendulum makes with the vertical is (take $g = 10\,\frac{m}{{{s^2}}}$)

Three charges are placed as shown in figure. The magnitude of $q_1$ is $2.00\, \mu C$, but its sign and the value of the charge $q_2$ are not known. Charge $q_3$ is $+4.00\, \mu C$, and the net force on $q_3$ is entirely in the negative $x-$ direction. The magnitude of $q_2$ is

Two point charges $q_{ A }=3\; \mu \,C$ and $q_{ B }=-3\; \mu \,C$ are located $20\; cm$ apart in vacuum.

$(a)$ What is the electric field at the midpoint $O$ of the line $AB$ joining the two charges?

$(b)$ If a negative test charge of magnitude $1.5 \times 10^{-9}\; C$ is placed at this point, what is the force experienced by the test charge?