[tex]\displaystyle \\
\texttt{Se da :} \\
t = 20 ~s \\
I = 2~mA = 0,002~A\\
Q = 8~J \\
\texttt{Se cere :} \\
R = ? \\ \\
\texttt{Rezolvare: } \\ \\
P = \frac{Q}{t} = \frac{8}{20} J/s = 0,4~J/s =\boxed{ 0,4~W }\\ \\
P = U \times I \\ \\
U = \frac{P}{I} = \frac{0,4}{0,002} = \frac{400}{2} = \boxed{200 ~V} \\ \\
R = \frac{U}{I} = \frac{200}{0,002} = \frac{200000}{2} = 100000~ \Omega = \boxed{\boxed{100~K\Omega}}[/tex]
