Question

Answer 1

a, \(R=\dfrac{U}{I_A}=\dfrac{12}{0,5}=24\left(\Omega\right)\)

\(\Rightarrow R_{1234}=R-R_5-R_a=22\left(\Omega\right)\)

\(\dfrac{1}{R_{1234}}=\dfrac{1}{R_{12}}+\dfrac{1}{R_{34}}\)<=> \(\dfrac{1}{22}=\dfrac{1}{R_{12}}+\dfrac{1}{12}\)

=> âm ??? bn xem lại đề 

 

 

Answer 2

a, K mở

Ampe kế chỉ 0,5 A\(=>Im=0,5A\)

\(Rtd=\dfrac{U}{Im}=\dfrac{12}{0,5}=24\left(om\right)\)

\(R1234=\dfrac{\left(R1+R2\right)\left(R3+R4\right)}{R1+R2+R3+R4}=R-R5-Ra\)

\(=\dfrac{\left(12+R2\right)\left(4+8\right)}{24+R2}=24-2=22=>R2=-38,4\left(??\right)\)

đề sai