CTM: \(R_1nt\left(R_2//R_3\right)\)
\(R_{23}=\dfrac{R_2\cdot R_3}{R_2+R_3}=\dfrac{10\cdot10}{10+10}=5\Omega\)
\(R_{123}=R_1+R_{23}=3+5=8\Omega\)
a)\(R_{tđ}=R_{123}=8\Omega\)
b)\(I=\dfrac{\xi}{r+R}=\dfrac{9}{1+8}=1A\)
c)\(U_N=\xi-I\cdot r=9-1\cdot1=8V\)
\(I_{123}=I=1A\Rightarrow U_3=U_{23}=U-U_1=8-1\cdot3=5V\)
\(P_3=\dfrac{U_3^2}{R_3}=\dfrac{5^2}{10}=2,5W\)