Đáp án:
$\begin{array}{l}
a.\dfrac{{{R_2}}}{{{R_1}}} = 5\\
b.\dfrac{{{I_1}}}{{{I_2}}} = 15
\end{array}$
Giải thích các bước giải:
a. Ta có:
$\dfrac{{{R_1}}}{{{R_2}}} = \dfrac{{{l_1}}}{{{l_2}}} = \dfrac{{16}}{{80}} = \dfrac{1}{5} \Rightarrow \dfrac{{{R_2}}}{{{R_1}}} = 5$
b. Lại có:
$\begin{array}{l}
{U_1} = 3{U_2} \Leftrightarrow \dfrac{{{U_1}}}{{{U_2}}} = 3 \Leftrightarrow \dfrac{{{I_1}}}{{{I_2}}}.\dfrac{{{R_1}}}{{{R_2}}} = 3\\
\Leftrightarrow \dfrac{{{I_1}}}{{{I_2}}}.\dfrac{1}{5} = 3 \Rightarrow \dfrac{{{I_1}}}{{{I_2}}} = 15
\end{array}$
