Question

giúp mình với

Answer 1

\(U=I_AR_2=2R_2\).

Ta có: \(R_N=\dfrac{R_1R_2}{R_1+R_2}=\dfrac{3R_2}{R_2+3}\)

Suy ra: \(I=\dfrac{E}{R_N+r}=\dfrac{18\left(R_2+3\right)}{8R_2+15}\left(1\right)\).

Mặt khác: \(I=\dfrac{U}{R_N}=\dfrac{2\left(R_2+3\right)}{3}\left(2\right)\).

\(\left(1\right),\left(2\right)\) cho ta: \(R_2=1,5\left(\Omega\right)\)