A.i、u、e B.I、U、E C.Im、Um、Em D.i、I、Im
一正弦交流電壓波形如圖所示,其瞬時值表達式為()伏。
A.u=10sin(ωt-π/2) B.u=10sin(ωt+π) C.u=-10sin(ωt-π/2) D.u=-10sin(ωt+π)
A.e=220sin(314t+30°) B.e=220sin(314t-30°) C.e=-220sin(314t+30°) D.e=-220sin(314t-30°)