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85问答库 > 请问永久磁铁的原理是什么。为什么还要用开关控制？

请问永久磁铁的原理是什么。为什么还要用开关控制？

2025-04-04 15:13:07

推荐回答（1个）

回答1：

要产生电，就需要导线切割磁感应线，因此，发电机中需要一个磁场。
用电流产生发电机的磁场就是励磁。
微型发电机的磁场也有永磁体的，但永磁体产生的磁场强度不足够高，因而，除微型发电机外的大多数发电机用电流励磁。

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