Skip to main content

What is a permanent magnet?

A permanent magnet is one in which the magnetic property is inherent to the material itself, as opposed to being induced by some external action such as an electrical current.


Magnetism arises from a sub-atomic property called spin, which has no classical analogue, but can be thought of as being somewhat similar to rotation. The "direction" of the spin matters for a variety of atomic conditions, such as the Pauli Exclusion Principle, which states that the orbitals in an atom can only hold two electrons at a time, and those electrons must have opposite spins. Electrons in different orbitals are allowed to have the same spin. Spin is an electromagnetic property, and if two spins are in opposition to each other, their magnetic effect cancels out. If there are two or more unpaired electrons, however, they will produce a net magnetic effect.


Iron is the most common example of a magnetic material, but others such as liquid oxygen can also behave like permanent magnets due to these unpaired electrons. The real key is not just to have an atom with unpaired electrons, but also to get all those atoms to align their spins in the same direction, rather than randomly. When this happens, the magnetic effect will become apparent at the macroscopic level. 

Comments

Post a Comment

Popular posts from this blog

Is there a word/phrase for "unperformant"?

As a software engineer, I need to sometimes describe a piece of code as something that lacks performance or was not written with performance in mind. Example: This kind of coding style leads to unmaintainable and unperformant code. Based on my Google searches, this isn't a real word. What is the correct way to describe this? EDIT My usage of "performance" here is in regard to speed and efficiency. For example, the better the performance of code the faster the application runs. My question and example target the negative definition, which is in reference to preventing inefficient coding practices. Answer This kind of coding style leads to unmaintainable and unperformant code. In my opinion, reads more easily as: This coding style leads to unmaintainable and poorly performing code. The key to well-written documentation and reports lies in ease of understanding. Adding poorly understood words such as performant decreases that ease. In addressing the use of such a poorly ...
Post a Comment
Read more

Is 'efficate' a word in English?

I routinely hear the word "efficate" being used. For example, "The most powerful way to efficate a change in the system is to participate." I do not find entries for this word in common English dictionaries, but I do not have an unabridged dictionary. I have checked the OED (I'm not sure if it is considered unabridged), and it has no entry for "efficate". It does have an entry for "efficiate", which is used in the same way. Wordnik has an entry for "efficate" with over 1800 hits, thus providing some evidence for the frequency of use. I personally like the word and find the meaning very clear and obvious when others use it. If it's not currently an "officially documented" word, perhaps its continued use will result in it being better documented.
Post a Comment
Read more