30.交流電流 i t = 50sin377 A ,此電流有效值為:
(A)100 A
(B)50$\sqrt{2}$ A
(C)25$\sqrt{2}$ A
(D)15.9 A
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統計: A(10), B(77), C(451), D(7), E(0) #1686604
統計: A(10), B(77), C(451), D(7), E(0) #1686604