單項(xiàng)選擇題某正弦電流的有效值為7.07A,頻率f=100Hz,初相角φ=-60°,則該電流的瞬時(shí)表達(dá)式為()

A.i=5sin(100πt-60°)A.
B.i=7.07sin(100nt+30°)A.
C.i=10sin(200πt-60°)A.
D.i=7.07sin(100πt-30°)A.