關於磁的問題-10分

Question

1.乜磁石都可以冇極性架咩?點解我有本補充練習話"A magnet may have no polarity i.e. ring magnet."當中所指的ring magnet又是甚麼呢?
2.天然磁石的磁力會否逐漸減弱,甚至消失?
3.乜磁化磁體或把磁體退磁的過程也會產生熱的嗎?

Answer 1

1. A ring magnet does have polarity, but they are joining together end to end (you may consider a ring magnet as a series of very small sections of bar magnets joining together). There is still magnetic flux inside the ring magnetic.

2. Yes. Elevated temperature may cause more vigorous thermal vibration of the magnetic dipoles inside a magnet. This will de-orientate the alignment of the dipoles and hence reduce the magnetization.

3. Magnetization or demagnetization is the process in which the atomic dipoles are made respectively aligned in an orderly manner or de-aligned to a random orientation. The agitation (friction) among the atomic dipoles and their neighbours produces heat,

Answer 2

1)話明磁石就一定有磁性, 但唔一定有極性. ring magnet 即係 "O" 形果D.
2)會, 如果同D有極性的野放埋一齊, 放耐D, 有機會變.
3) 唔名問乜.