Question

Answer 1

K mở =>R1 nt (R3//R4) gọi \(R3=x\left(\Omega\right)\)

\(=>I1=Ia+I3=>0,5=I1-I3\)

\(=>I1=I34=Im=\dfrac{Uab}{Rtd}=\dfrac{16}{R1+\dfrac{R4.x}{R4+x}}=\dfrac{16}{12+\dfrac{8x}{8+x}}=\dfrac{16}{\dfrac{96+20x}{8+x}}=\dfrac{16\left(8+x\right)}{96+20x}\left(A\right)\)

\(\)\(=>I3=\dfrac{U34}{x}=\dfrac{I34.R34}{x}=\dfrac{\dfrac{16\left(8+x\right)}{96+20x}.\dfrac{8x}{8+x}}{x}\left(A\right)\)

\(=>0,5=\dfrac{16\left(8+x\right)}{96+20x}-\dfrac{\dfrac{16\left(8+x\right)}{96+20x}.\dfrac{8x}{8+x}}{x}=>x=R3=8\Omega\)