Đáp án:
400000 vòng
Giải thích các bước giải:
Ta có:
\({P_{hp}} = {\left( {\dfrac{P}{{{U_2}}}} \right)^2}R \Rightarrow \dfrac{{{P_{hp}}'}}{{{P_{hp}}}} = {\left( {\dfrac{{{U_2}}}{{{U_2}'}}} \right)^2} = \dfrac{1}{{100}} \Rightarrow {U_2}' = 10{U_2}\)
Mặt khác:
\(\begin{array}{l}
\dfrac{{{U_1}}}{{{U_2}'}} = \dfrac{{{n_1}}}{{{n_2}'}}\\
\Rightarrow {n_2}' = {n_1}.\dfrac{{{U_2}'}}{{{U_1}}} = {n_1}.\dfrac{{10{U_2}}}{{{U_1}}} = {n_1}.\dfrac{{10{n_2}}}{{{n_1}}} = 10{n_2} = 400000
\end{array}\)
