【简答题】磁铁为什么能吸铁而不能吸铜、铝等金属？

【单选题】Questions 57 to 61 are based on the following passage. Within fifteen years Britain and other nations should be well on with the building of huge industrial architectures for the recycling of waste. T...

【单选题】Questions 57 to 61 are based on the following passage. Within fifteen years Britain and other nations should be well on with the building of huge industrial architectures for the recycling of waste. T...

【单选题】永久磁铁的磁通是（）。

【简答题】有一额定电压为220V的直流电磁铁，若把它接在220V的交流电源上，会发生什么现象？

【单选题】纯磁铁的分子式是（）。

【判断题】Mn-ZnFe 2 O 4 铁氧体晶粒越大,起始磁导率越大,矫顽力越小。( )

【单选题】名词翻译:磁铁

【单选题】Within fifteen years Britain and other nations should be well on with the building of huge industrial architectures for the recycling of waste. The word rubbish could lose its meaning because everythi...

【判断题】地球是一块磁铁。