Đáp án:
42:C
43:C
45: B
46C
Giải thích các bước giải:
42:
\[R = \frac{U}{I} = \frac{{24}}{{1,2}} = 20\Omega \]
\[R' = R + 10 = 30\Omega \]
\[U' = R'.I = 30.1,2 = 36V\]
43:
\[R = \frac{U}{I} = \frac{5}{{{{100.10}^{ - 3}}}} = 50\Omega \]
\[I' = \frac{{U'}}{R} = \frac{{5 + 20\% .5}}{{50}} = 0,12A = 120m.A\]
44: gdaaeqaaaaakiabg2da9iaa
% ikdaaaa!3FE8!
\[\frac{{{I_1}}}{{{I_2}}} = \frac{{{R_2}}}{{{R_1}}} = 2\]
\[{R_2} = 2{R_1}\]
45:
\[\frac{{{I_1}}}{{{I_2}}} = \frac{{{R_2}}}{{{R_1}}} = \frac{1}{2} = > {I_2} = 2{I_1}\]
56:
\[\frac{{{I_1}}}{{{I_2}}} = \frac{{{U_1}}}{{{U_2}}} = \frac{1}{4} = > {U_2} = 4{U_1}\]