[tex]t=10 min=600 s\\U_1=R_1I=>I=\frac{U_1}{R_1}=\frac{8}{4}=2A=>I=2A \\R_1,R_2->serie=>U_{AB}=U_1+U_2=>U_2=U_{AB}-U_1=10-8=2 V\\U_2=R_2I=>R_2=\frac{U_2}{I}=\frac{2}{2}=1\Omega\\ P=EI=12*2=24 W=>P=24W\\R_e=R_1+R_2=4+1=5 \Omega\\I=\frac{E}{R_e+r}<=>IR_e+Ir=E=>r=\frac{E-IR_e}{I}=\frac{12-2*5}{2}=\frac{2}{2}=1 \Omega=>r=1\Omega\\ W_2=U_2It=2*2*600=2400 J=>W_2=2400 J[/tex]
