H24
MY
16 tháng 8 2021 lúc 6:25

=>R1//{R2 nt ( R3 // R4)}

\(=>U234=U1=Uab=12V\)

\(=>I1=\dfrac{U1}{R1}=\dfrac{18}{3}=6A\)

\(=>I234=I34=\dfrac{U234}{R234}=\dfrac{18}{R2+\dfrac{R3.R4}{R3+R4}}=\dfrac{18}{6+\dfrac{4.12}{4+12}}=2A\)

\(\)\(=>U34=U3=I34.\dfrac{R3R4}{R3+R4}=2.\dfrac{4.12}{4+12}=6V\)

\(=>I3=\dfrac{U3}{R3}=\dfrac{6}{4}=1,5A\)

\(=>I1=I3+Ia=>Ia=I1-I3=6-1,5=4,5A\)

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