Ta có: \(\overrightarrow {{E_M}} = \overrightarrow {{E_1}} + \overrightarrow {{E_2}} \)
Do \(\left\{ \begin{array}{l}{q_1} = {q_2}\\AM = MB\end{array} \right.\) ta suy ra \({E_1} = {E_2} = k\dfrac{{\left| {{q_1}} \right|}}{{A{M^2}}}\)
Lại có \(\overrightarrow {{E_1}} \uparrow \downarrow \overrightarrow {{E_2}} \)
\( \Rightarrow {E_M} = {E_1} - {E_2} = 0V/m\)