问题
问答题 简答题
运行中的变压器为什么会有“嗡嗡”声？
答案
参考答案：
变压器一接上电源，就有“嗡嗡”的响声，这是由于铁芯中交变的磁通在铁芯硅钢片间产生一种力的振动的结果，一般来说，这种“嗡嗡”的大小与加在变压器上的电压和电流成正比。
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运行中的变压器为什么会有“嗡嗡”声？
参考答案：
变压器一接上电源，就有“嗡嗡”的响声，这是由于铁芯中交变的磁通在铁芯硅钢片间产生一种力的振动的结果，一般来说，这种“嗡嗡”的大小与加在变压器上的电压和电流成正比。
| 阅读理解。 | ||||||||||||
From: Liu Mei To: Zhang Li Time: Six o'clock Message: She wants you to have a picnic with her at eight this Sunday. Tel: 8556-7677 Dad | ||||||||||||
| 根据表格内容，选择正确的答案。 | ||||||||||||
| 1. How many students go to have a picnic? | ||||||||||||
| A. Two. B. Three. C. Five. D. Seven. | ||||||||||||
| 2. What food do they take for the picnic? | ||||||||||||
| A. Bread, chicken and rice. B. Orange, juice and milk. C. Bread, orange and rice. D. Orange, juice, milk and chicken. | ||||||||||||
| 3. Who answers the telephone(接电话)? | ||||||||||||
| A. Liu Mei. B. Zhang Li. C. Liu Mei' dad. D. Zhang Li's dad. | ||||||||||||
| 4. They want to go for a picnic______. | ||||||||||||
| A. at seven B. at eight on Sunday C. at six on Sunday D. at six and eight on Sunday | ||||||||||||
| 5. 8556-7677 is _____telephone number. | ||||||||||||
A. Zhang Li's | ||||||||||||