Question

 

Answer 1

\(R_{tđ}=R_1+R_2+R_3=15+5+8=28\left(\Omega\right)\)

\(I=I_1=I_2=\dfrac{U}{R_{tđ}}=\dfrac{9}{28}\left(A\right)\)

\(\left\{{}\begin{matrix}U_1=I_1.R_1=\dfrac{9}{28}.15=\dfrac{135}{28}\left(V\right)\\U_2=I_2.R_2=\dfrac{9}{28}.5=\dfrac{45}{28}\left(V\right)\\U_3=I_3.R_3=\dfrac{9}{28}.8=\dfrac{18}{7}\left(V\right)\end{matrix}\right.\)

\(R=\rho\dfrac{l}{S}=1,7.10^{-8}.\dfrac{100}{0,1.10^{-6}}=17\left(\Omega\right)\)

\(U_d=I.R=\dfrac{9}{28}.17=\dfrac{153}{28}\left(V\right)\)