Câu 2.
\(R_{13}=\dfrac{R_1\cdot R_3}{R_1+R_3}=\dfrac{30\cdot60}{30+60}=20\Omega\)
\(R_{tđ}=R_2+R_{13}=45+20=65\Omega\)
\(I_m=\dfrac{U}{R}=\dfrac{130}{65}=2A\)
\(I_{13}=I_m=2A\)
\(U_{13}=U-U_2=U-I_2\cdot R_2=130-2\cdot45=40V\)
\(R_1//R_3\Rightarrow U_1=U_3=U_{13}=40V\)
\(I_3=\dfrac{U_3}{R_3}=\dfrac{40}{60}=\dfrac{2}{3}A\)
Câu 3.
\(R_1//R_2\)
\(\Rightarrow R_{tđ}=\dfrac{R_1\cdot R_2}{R_1+R_2}=\dfrac{10\cdot30}{10+30}=7,5\Omega\)
\(U_1=U_2=U_m=15V\)
\(I_1=\dfrac{U_1}{R_1}=\dfrac{15}{10}=1,5A\)
\(I_2=\dfrac{U_2}{R_2}=\dfrac{15}{30}=0,5A\)
\(I_m=I_1+I_2=1,5+0,5=2A\)