\(MCD:R_1nt\left[\left(R_2ntR_3\right)//\left(R_4ntR_5\right)\right]ntR_6\)
\(\Rightarrow R_{td}=R_1+R_{2345}+R_6=4+\dfrac{\left(8+8\right)\cdot\left(4+12\right)}{8+8+4+12}+4=16\Omega\)
\(\rightarrow I_{AB}=I_1=I_{2345}=I_6=\dfrac{U_{AB}}{R_{td}}=\dfrac{12}{16}=0,75A\)
Ta có: \(\dfrac{I_{23}}{I_{45}}=\dfrac{R_{45}}{R_{23}}=\dfrac{16}{8}=2\)
\(\Rightarrow I_{23}=2I_{45}\)
Ta có: \(I_{2345}=I_{23}+I_{45}=3I_{45}\Rightarrow I_{45}=I_4=I_5=\dfrac{I_{2345}}{3}=\dfrac{0,75}{3}=0,25A\)
\(\rightarrow I_{23}=I_2=I_3=I_{2345}-I_{45}=0,75-0,25=0,5A\)
\(\rightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}U_1=I_1\cdot R_1=0,75\cdot4=3V\\U_6=U_1=3V\end{matrix}\right.\\\left[{}\begin{matrix}U_2=I_2\cdot R_2=0,5\cdot8=4V\\U_3=I_3\cdot R_3=0,5\cdot8=4V\end{matrix}\right.\\\left[{}\begin{matrix}U_4=I_4\cdot R_4=0,25\cdot4=1V\\U_5=I_5\cdot R_5=0,25\cdot12=3V\end{matrix}\right.\end{matrix}\right.\)
\(\rightarrow P_3=U_3\cdot I_3=4\cdot0,5=2\)(W)
\(\rightarrow P_{AB}=U_{AB}\cdot I_{AB}=12\cdot0,75=9\)(W)
\(\rightarrow U_{MN}=U_4+U_2=U_2-U_4=4-1=3V\)
\(\rightarrow U_{NB}=U_5+U_6=3+3=6V\)
