Đáp án:
\(\begin{array}{l}
1.\\
F = 8,{1.10^{ - 4}}N\\
b.\\
E = 117000V/m\\
2.\\
a.\\
R = 7\Omega
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
1.\\
F = \frac{{k|{q_1}{q_2}|}}{{A{B^2}}} = {9.10^9}.\frac{{|{{4.10}^{ - 8}}. - {{9.10}^{ - 8}}|}}{{0,{2^2}}} = 8,{1.10^{ - 4}}N\\
b.\\
{E_{AM}} = \frac{{k|{q_1}|}}{{{{\frac{{AB}}{2}}^2}}} = \frac{{{{9.10}^9}{{.4.10}^{ - 8}}}}{{{{\frac{{0,2}}{1}}^2}}} = 36000V/m\\
{E_{BM}} = \frac{{k|{q_2}|}}{{{{\frac{{AB}}{2}}^2}}} = \frac{{{{9.10}^9}.| - {{9.10}^{ - 8}}|}}{{{{\frac{{0,2}}{1}}^2}}} = 81000V/m\\
E = {E_{AM}} + {E_{BM}} = 36000 + 81000 = 117000V/m\\
2.\\
a.\\
R = {R_1} + \frac{{R{R_2}}}{{R + {R_2}}} = 5 + \frac{{6.3}}{{6 + 3}} = 7\Omega
\end{array}\)
