\(M_NCD:\left(R_1ntR_2\right)//R_3\)
a.
\(\rightarrow R_N=\dfrac{\left(R_1+R_2\right)\cdot R_3}{R_1+R_2+R_3}=.....\Omega\)
\(\rightarrow I=\dfrac{U_N}{R_N}=.....A\)
\(\rightarrow\xi=I\left(R_N+r\right)=IR_N+Ir=.....V\)
b.
Ta có: \(P_N=U_NI_N=....\)W
\(\rightarrow P_{ng}=\xi I_N=.....\)W