问题
填空题
用U1和U2的两种电压通过相同长度和材料的导线输电，若输送的电功率相等，在输电线上损失的电功率也相等，在两种情况下输电线截面积之比S1:S2为_____
答案
U22：U12
在输电线上损失的电功率相等，有：
，而
、
，
、
，代入得：S1:S2= U22：U12
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用U1和U2的两种电压通过相同长度和材料的导线输电，若输送的电功率相等，在输电线上损失的电功率也相等，在两种情况下输电线截面积之比S1:S2为_____
U22：U12
在输电线上损失的电功率相等，有：，而、，、，代入得：S1:S2= U22：U12
| 选词填空。 根据所给句子选用方框内的词语填空(有多余选项)，注意用其适当的形式。 | |
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