Question

cho đoạn mạch điện (R1//R2)nối tiếp R3. U=84V, R1=2R2, R3=10, I=6A. Tính a) Rtđ, b) tính I1,I2

Answer 1

\(R_{tđ}=\dfrac{U}{I}=\dfrac{84}{6}=14\Omega\)

\(R_{12}=14-10=4\Omega\)

\(R_1//R_2\Rightarrow R_{12}=\dfrac{R_1\cdot R_2}{R_1+R_2}=\dfrac{R_2^2}{2R_2}=\dfrac{R_2}{2}=4\)

\(\Rightarrow\left\{{}\begin{matrix}R_2=8\Omega\\R_1=16\Omega\end{matrix}\right.\)

\(U_1=U_2=U_{12}=U-U_3=84-10\cdot6=24V\)
\(I_1=\dfrac{U_1}{R_1}=\dfrac{24}{16}=1,5A\)

\(I_2=\dfrac{U_2}{R_2}=\dfrac{24}{8}=3\Omega\)