题目内容
(请给出正确答案)
[主观题]
正弦交流电流的频率为50Hz,有效值是1A,初相角90°,其瞬时值表达式为()。
A.i(t)=sin(314t+90°)A
B.i(t)= sin(314t+90°)A
C.i(t)=cos(314t+90°)A
D.i(t)= cos(314t+90°)A
答案
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A.i(t)=sin(314t+90°)A
B.i(t)= sin(314t+90°)A
C.i(t)=cos(314t+90°)A
D.i(t)= cos(314t+90°)A
第1题
A.
C.
某正弦电压有效值为380V,频率为50Hz,计时始数值等于380V,其瞬时值表达式为
第2题
A.1A,50Hz,300
B.1A,100Hz,-300
C.0.707A,100Hz,300
D.0.707A,50Hz,300
第6题
A.i=5sin(100πt+30°)A
B.i=7.07sin(100πt-60°)A
C.i=10sin(200πt-60°)A
D.i=7.07sin(100t+60°)A
第7题
(1)写出此正弦电压的时间函数表达式;
(2)计算t=0,0.0025s,0.0075s,0.0100s,0.0125s,0.0175s的电压瞬时值;
(3)绘出波形图.
第9题
A.e=220sin(314t+30°)v
B.e=22#2sin(314t+30°)v
C.e=220sin(314t-30°)v
D.e=22#2sim(314t-30°)v