\(R_{tđ}=R_1+R_2+R_3=6+12+20=38\Omega\)
\(I_3=I=\dfrac{U}{R}=\dfrac{36}{38}=\dfrac{18}{19}A\)
\(U_2=I_2\cdot R_2=\dfrac{18}{19}\cdot12=\dfrac{216}{19}V\)
\(P=U\cdot I=36\cdot\dfrac{18}{19}=\dfrac{648}{19}W\)
\(A=P\cdot t=\dfrac{648}{19}\cdot30\cdot60=61389,5J\)
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\(MCD:R1ntR2ntR3\)
\(=>R=R1=R2=R3=6+12+20=38\Omega\)
\(=>I=I1=I2=I3=U:R=36:38=\dfrac{18}{19}A\)
\(=>U2=I2\cdot R2=\dfrac{18}{19}\cdot12=\dfrac{216}{19}V\)
\(=>A=UIt=36\cdot\dfrac{18}{19}\cdot\dfrac{30}{60}=\dfrac{324}{19}\)Wh
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