\(MCD:R_1//R_2//R_3\)
\(\Rightarrow\dfrac{1}{R}=\dfrac{1}{R_1}+\dfrac{1}{R_2}+\dfrac{1}{R_3}=\dfrac{1}{40}+\dfrac{1}{30}+\dfrac{1}{20}=\dfrac{13}{120}\)
\(\Rightarrow R=\dfrac{120}{13}\Omega\)
Ta có: \(U=U_1=U_2=U_3=I_1\cdot R_1=0,2\cdot40=8V\)
\(\Rightarrow\left\{{}\begin{matrix}I_3=\dfrac{U_3}{R_3}=\dfrac{8}{20}=0,4A\\I=\dfrac{U}{R}=\dfrac{8}{\dfrac{120}{13}}=\dfrac{13}{15}A\end{matrix}\right.\)
\(A=UIt=8\cdot\dfrac{13}{15}\cdot\dfrac{10}{60}\cdot365=\dfrac{3796}{9}\)(Wh)
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