\(MCD:R_1ntR_2\)
\(\Rightarrow R_{td}=R_1+R_2=10+20=30\Omega\)
Ta có: \(I=I_1=I_2=\dfrac{U}{R_{td}}=\dfrac{120}{30}=4A\Rightarrow\left[{}\begin{matrix}U_1=I_1R_1=4\cdot10=40V\\U_2=I_2R_2=4\cdot20=80V\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}P_1=U_1I_1=40\cdot4=160W\\Q_{toa}=A=U_1I_1t=160\cdot5\cdot60=48000J\approx13,\left(3\right)Wh\end{matrix}\right.\\\left\{{}\begin{matrix}P_2=U_2I_2=80\cdot4=320W\\Q_{toa}=A=U_2I_2t=320\cdot5\cdot60=96000J\approx26,\left(6\right)Wh\end{matrix}\right.\end{matrix}\right.\)
Ta có: \(Q=A=UIt=120\cdot4\cdot\dfrac{5}{60}=40\)Wh = 0,04kWh
Vậy công tơ điện tăng thêm 0,04 số.
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