Đáp án:
\(\begin{array}{l}
a.{I_2} = 4A\\
b.{Q_1} = 38400J\\
c.Q = 76800J
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\\
{R_{23}} = {R_2} + {R_3} = 20 + 10 = 30\Omega \\
U = {U_1} = {U_{23}} = 120V\\
{I_2} = {I_3} = {I_{23}} = \dfrac{{{U_{23}}}}{{{R_{23}}}} = \dfrac{{120}}{{30}} = 4A\\
b.\\
{I_1} = \dfrac{{{U_1}}}{{{R_1}}} = \dfrac{{120}}{{30}} = 4A\\
{Q_1} = {R_1}I_1^2t = {30.4^2}.80 = 38400J\\
c.\\
R = \dfrac{{{R_1}{R_{23}}}}{{{R_1} + {R_{23}}}} = \dfrac{{30.30}}{{30 + 30}} = 15\Omega \\
I = {I_{23}} + {I_1} = 4 + 4 = 8A\\
Q = R{I^2}t = {15.8^2}.80 = 76800J
\end{array}\)
