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13问答网 > 电功率计算中，为什么不能用ΔP=ΔU*ΔI求出变化的电功率？

电功率计算中，为什么不能用ΔP=ΔU*ΔI求出变化的电功率？

2025-03-15 10:04:12

推荐回答（4个）

回答1：

你要明白ΔP等于啥，怎么推倒啊~
ΔP=P初始-P后来
设初始电压是U，后来变化ΔU，电流是I，后来变化ΔI
ΔP=U*I-(U+ΔU)(I+ΔI)=-ΔU*ΔI-U*ΔI-ΔU*I
当然这个正负号是和ΔU、ΔI正负号有关的。所以你看ΔP不等于ΔU*ΔI

回答2：

晕，你用ΔP=P2-P1=U2I2-U1I1=(U1+ΔU)(I1+ΔI)-U1I1你自己算下酒知道了不等于ΔU*ΔI

回答3：

其实我不太明白为什么问这个问题,ΔP=ΔU*ΔI+U*ΔI+ΔU*I的吧

回答4：

U=U*+ΔU*，I=I*+ΔI，P=UI，P*=U*I*,ΔP=P-P*
ΔP=ΔU*ΔI+U*ΔI+ΔU*

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