Đáp án:

Giải thích các bước giải:

cho mik ctlhn :<

Ta có:

$I_{1}=\dfrac{U_{V_{1}}}{R_{1}}=\dfrac{2}{R_{1}}$

$I_{V_{1}}=\dfrac{U_{V_{1}}}{R_{v}}=\dfrac{2}{R_{v}}$

$I_{2}=\dfrac{U_{V_{2}}}{R_{2}}=\dfrac{3}{2R_{1}}$

$I_{V_{2}}=\dfrac{U_{V_{2}}}{R_{v}}=\dfrac{3}{R_{v}}$

Ta có: $I_{1}+I_{V_{1}}=I_{2}+I_{V_{2}}$

$⇔\dfrac{2}{R_{1}}+\dfrac{2}{R_{v}}=\dfrac{3}{2R_{1}}+\dfrac{3}{R_{v}}$

$⇔\dfrac{1}{2R_{1}}=\dfrac{1}{R_{v}}$

$⇒R_{v}=2R_{1}$

$R=\dfrac{R_{1}.R_{v}}{R_{1}+R_{v}}+\dfrac{2R_{1}.R_{v}}{2R_{1}+R_{v}}$

$=\dfrac{2.R_{1}²}{3R_{1}}+\dfrac{4R_{1}²}{4R_{1}}$

$=\dfrac{2R_{1}}{3}+R_{1}$

$=\dfrac{5R_{1}}{3}$

$=\dfrac{5R_{v}}{6}$

$⇒\dfrac{R_{v}}{R}=\dfrac{6}{5}$