写出下列各电流向量所对应的正弦量表达式(角频率为ω)。1=3+j4A,i1=_______A;2=-j10A,i2=_______A;
A: 5sin(t+53.10);10sin(t-900)
B: 5sin(t-53.10);10sin(t+900)
C: 5sin(t+53.10);10sin(t-900)
D: 5sin(t-53.10);10sin(t+900)
A: 5sin(t+53.10);10sin(t-900)
B: 5sin(t-53.10);10sin(t+900)
C: 5sin(t+53.10);10sin(t-900)
D: 5sin(t-53.10);10sin(t+900)
举一反三
- 将正弦电压u = 10 sin( 314 t +30 ) V 施加于感抗XL = 5 的电感元件上,<br/>则通过该元件的电流 i = ( ) 。 A: 50 sin( 314 t +90 ) B: 2 sin( 314 t +60 ) C: 2 sin( 314 t -60 ) D: 2 sin( 314 t -30 )
- 对称三相负载三角形连接,若相电流iab=10[img=41x45]17e0b6a8592d8be.jpg[/img] sin(ωt十30o)A,则线电流iC为_______。 A: 10sinωt A B: 30 sin(ωt+60o) A C: 30 sin(ωt+120 o ) A D: 30sinωt A
- 下列信号中,( )信号的频谱是连续的。 A: $x(t) = A\sin (\omega t + {\varphi _1}) + B\sin (3\omega t + {\varphi _2})$ B: $x(t) = 5\sin 30t + 3\sin \sqrt {50} t$ C: $x(t) = {e^{ - at}}\sin {\omega _0}t$
- 设\(z = {e^{x - 2y}}\),而\(x = \sin t,\;y = {t^3},\)则\( { { dz} \over {dt}} = \)( ) A: \({e^{\sin t - 2{t^3}}}\) B: \({e^{\sin t - 2{t^3}}}\left( {\cos t - 6{t^2}} \right)\) C: \({e^{\sin t - 2{t^3}}}\ {\sin t } \) D: \({e^{\sin t - 2{t^3}}}\,{t^3}\)
- 一阶常微分方程[img=152x26]1802e4d6075ee4f.png[/img]的通解为 A: sin(2*t)/5-cos(2*t)/10+C*exp(-4*t) B: sin(2*t)/7+cos(2*t)/5-C*exp(-3*t) C: sin(2*t)/7-C*cos(2*t)/10+C*exp(-2*t) D: sin(2*t)/7-cos(2*t)/7+C*exp(-5*t)