Đáp án:
\(\begin{array}{l}
a.\\
{E_b} = 4,5V\\
{r_b} = 0,75\Omega \\
b.\\
I = 0,5A\\
P = 2,0625W\\
c.\\
{R_3} = \frac{{28}}{3}\Omega
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
a.\\
{E_b} = \frac{3}{2}E = 1,5.3 = 4,5V\\
{r_b} = \frac{3}{2}r = 1,5.0,5 = 0,75\Omega \\
b.\\
R = \frac{{{R_2}{R_3}}}{{{R_2}{R_3}}} + {R_1} = \frac{{12.6}}{{12 + 6}} + 4,25 = 8,25\Omega \\
I = \frac{{{E_b}}}{{R + {r_b}}} = \frac{{4,5}}{{8,25 + 0,75}} = 0,5A\\
P = R{I^2} = 8,25.0,{5^2} = 2,0625W\\
c.\\
R = \frac{{{R_2}{R_3}}}{{{R_2}{R_3}}} + {R_1} = \frac{{12{R_3}}}{{12 + {R_3}}}\\
I = \frac{{{E_b}}}{{R + {r_b}}} = \frac{{4,5}}{{\frac{{12{R_3}}}{{12 + {R_3}}} + 0,75}} = 0,75A\\
{R_3} = \frac{{28}}{3}\Omega
\end{array}\)