Question

Tóm tắt 

\(R_2=10\Omega\)

\(R_3=40\Omega\)

\(I=3A\)

\(I_3=1A\)

a) \(U_{AB}=?V\)

b) \(R_{tđ}=?\Omega\)

    \(R_2=?\Omega\)

Answer 1

a)\(U_3=I_3\cdot R_3=1\cdot40=40V\)

\(R_3//\left(R_1ntR_2\right)\Rightarrow U=U_3=U_{12}=40V\)

b)\(R_{tđ}=\dfrac{U}{I}=\dfrac{40}{3}\Omega\)

\(R_{tđ}=\dfrac{R_{12}\cdot R_3}{R_{12}+R_3}=\dfrac{R_{12}\cdot40}{R_{12}+40}=\dfrac{40}{3}\Rightarrow R_{12}=20\)

\(R_1ntR_2\Rightarrow R_2=R_{12}-R_1=20-10=10\Omega\)