Two point charges $q_A$ and $q_B$ are placed at some separation on positive $x$-axis at points $\left(x_A, 0\right)$ and $\left(x_B, 0\right)$. It is given that $\left|q_A\right|>\left|q_B\right|$ and $x_B>x_A$. If the null point is the point where the net electric field due to both the charges is zero, then

Figure shows the electric field lines around three point charges $A$, $B$ and $C$.

Which charges are positive?

Figure shows the electric field lines around three point charges $A$, $B$ and $C$.

Which charge has the largest magnitude? Why?

Figure shows the electric field lines around three point charges $A$, $B$ and $C$.

Five charges, $q$ each are placed at the corners of a regular pentagon of side $a$.

What will be the electric field at $O$, the center of the pentagon?

Five charges, $q$ each are placed at the corners of a regular pentagon of side $a$.

What will be the electric field at $O$ if the charge from one of the corners (say $A$) is removed?

Five charges, $q$ each are placed at the corners of a regular pentagon of side $a$.

What will be the electric field at $O$ if the charge $q$ at $A$ is replaced by $-q$ ?

Five charges, $q$ each are placed at the corners of a regular pentagon of side $a$.

What will be the electric field at the center, if the pentagon is replaced by $n$-sided regular polygon with the charge $q$ at each of its corners?

The given figure gives electric lines of force due to two charges $q_1$and $q_2.$What are the signs of the two charges?