There are two charged particles of same nature, and they are fixed. The position of equilibrium for a third charge will be

In the given figure, if $Q_1$ and $Q_2$ are positive, where could a negative charge be placed to have vertically upward net force on it?

In the given figure, if the vertical distance from point $E$ to $B$ is the same as the horizontal from $D$

In the given figure, the vertical distance from point $E$ to $B$ is the same as the horizontal distance from $E$ to either charge and the electric field at $B$ due to either charge has magnitude $1.0\times {10}^6$. If $Q_1$ is negative and $Q_2$ is positive, what is the direction of the net electric field at $B$$?$