Đáp án:
245,91V/m
Giải thích các bước giải:
$\begin{gathered} \frac{1}{{A{H^2}}} = \frac{1}{{A{B^2}}} + \frac{1}{{A{C^2}}} \Rightarrow AH = 24cm \hfill \\ BH = 18cm;CH = 32cm \hfill \\ {E_A} = k\frac{{\left| q \right|}}{{A{H^2}}} = {9.10^9}.\frac{{{{10}^{ - 9}}}}{{0,{{24}^2}}} = 156,25V/m \hfill \\ {E_B} = k\frac{{\left| q \right|}}{{B{H^2}}} = 277,78V/m \hfill \\ {E_C} = k\frac{{\left| q \right|}}{{C{H^2}}} = 87,89V/m \hfill \\ \overrightarrow {{E_B}} //\overrightarrow {{E_C}} \Rightarrow {E_{BC}} = {E_B} - {E_C} = 189,89V/m \hfill \\ \Rightarrow E = \sqrt {E_A^2 + E_{BC}^2} = \sqrt {156,{{25}^2} + 189,{{89}^2}} = 245,91V/m \hfill \\ \end{gathered} $
