Magnetism and Entropy

[Hyperlite]

According to the laws of thermodynamics, the entropy of the universe is constantly increasing. Accordingly, a system will constantly move from order to disorder. However, I reminisced back to the elementary school days when simple experiments regarding magnets were performed. One such observation included emptying iron dust particles onto an overhead projection machine so that the area of projection was covered, then a magnet was introduced into the center of these iron dust particles and they suddenly arranged themselves in the fashion of the two magnetic poles. I was left to wonder if the introduction of the magnet could truly defy the entropy of the system. Just some thoughts..

[VendingMenace]

first off great question!

 

well, it doesn't really defy entropy, but it might be hard to see where the entropy might be going too. It is clear that the iron fillings are being ordered, but what you also must take into acount is that in order for the iron filings to be ordered, there must be a force applied and the iron fillings must be moved. This will require some energy. We can imagine that some of this energy will be lost to the surrounding area (friction with the surface as they are dragged about. ect) as heat and thus will increase the entropy of the surroundings. So there is at least one way that we can see entropy might be increased. There might be more, i am not sure. I don't really have time right now to think about this exhaustivily, though someone else here might.

 

As a more simplistic example consider the task of you cleaning your room (or a child stacking biulding blocks). Clearly the entropy of the room appears to decrease, as things are put away. But what you might fail to notice is that your body is doing work on these objects and in order to perform this work it must make energy. Durring the proccess of making energy, you body looses some of it to heat and this increases the entropy of the surroudnings.

 

As it turns out and increase in the heat introduced into a system often is associated with a increase in entropy (though not always!) and so it is usually a good idea to ask yourself "in what ways could i be loosing heat?" Many a time the answer will be either friction or heat lost durrring a chemical reaction.

 

 

Anyways, just a quick little answer. I hope it helps some

[VendingMenace]

arg...i realized that i mis-spoke (mis-typed?) yesterday and i would like to correct my self

 

I had said;

As it turns out and increase in the heat introduced into a system often is associated with a increase in entropy (though not always!)

 

Which i belive is acutally a bunch of rubbish

 

What i meant to say though was this;

 

Adding heat to a system usually increases the temperature, though there are some systems for which this is not true.

 

For example, gravitationally held systems (like our galaxy) have a negative heat capacity and as such adding heat will cause the temperature to decrease.

 

That is all i wanted to say.