Câu 12: A

Ta có:

\(\begin{array}{l}
F = P \Rightarrow Eq = mg\\
 \Rightarrow 1000.q = \dfrac{{{{10}^{ - 6}}}}{{1000}}.10\\
 \Rightarrow q = {10^{ - 11}}C
\end{array}\)

Câu 13: D

Ta có: 

\(\begin{array}{l}
\dfrac{1}{2}m\left( {v_2^2 - v_1^2} \right) = qEd\\
 \Rightarrow \dfrac{1}{2}{.10^{ - 11}}\left( {{{\left( {3,{{6.10}^4}} \right)}^2} - {{\left( {{{2.10}^4}} \right)}^2}} \right) = {5.10^{ - 5}}.E.0,05\\
 \Rightarrow E = 1792\left( {V/m} \right)
\end{array}\)

Câu 14: 

Ta có: 

\(\begin{array}{l}
E = I\left( {R + {R_0} + r} \right)\\
 \Rightarrow \left\{ \begin{array}{l}
E = \dfrac{1}{{100}}\left( {80 + 10 + r} \right)\\
E = \dfrac{1}{{60}}\left( {40 + 10 + r} \right)
\end{array} \right.\\
 \Rightarrow \left\{ \begin{array}{l}
E = 0,9 + 0,01r\\
E = \dfrac{5}{6} + \dfrac{r}{{60}}
\end{array} \right. \Rightarrow \left\{ \begin{array}{l}
E = 1V\\
r = 10\Omega 
\end{array} \right.
\end{array}\)