感抗为50Ω的电感线圈两端加电压为u=50sin(314t+60°)V,则通过线圈的电流为 (A)i=50sin(314t-30°)A; (B)i=sin(314t-30°)A; (C)i=sin(314t-60°)A; (D)i=50sin(314t-60°)A
答案见下图