Câu hỏi 31

Ta có: \(P = {I^2}R\) nên \({P_1} = {P_2}\;\)khi \({I_1}\; = {I_2}\)

\(\frac{{{E_1}}}{{{Z_1}}} = \frac{{{E_2}}}{{{Z_2}}} \Rightarrow \frac{{{{({\omega _1}NBS.\frac{1}{{\sqrt 2 }})}^2}}}{{{R^2} + {{(Z_{L1}^{} - {Z_{C1}})}^2}}} = \frac{{{{(1,89{\omega _1}NBS.\frac{1}{{\sqrt 2 }})}^2}}}{{{R^2} + {{(1,89Z_{L1}^{} - \frac{{{Z_{C1}}}}{{1,89}})}^2}}}\)

\( \Rightarrow \frac{1}{{69,{1^2} + {{({Z_{L1}} - 45)}^2}}} = \frac{{1,{{89}^2}}}{{69,{1^2} + {{(1,89{Z_{L1}} - \frac{{45}}{{1,89}})}^2}}} \Rightarrow {Z_L} = 81,8\Omega  \Rightarrow L = 0,65H\)

Chọn  A