Hi everyone and welcome to the new Megathread :) For my first Mega I want to share a special interest of mine: the magnetic field and how to understand its behavior intuitively.
I'm guessing most of us have played with magnets before at some point and have felt that mysterious force pushing them apart or pulling them together, depending on how the magnets are oriented toward each other. Some of you may have also seen diagrams like this
Or done an experiment where you visualize the magnetic field lines with iron filings like this
These lines represent the shape of the magnetic field. The way you can interpret them is that if you place a compass in the field, the compass will align with the field lines at that point. And the closer the lines are to each other, the stronger the magnetic field is in that area. Also, magnetic field lines always form closed loops. They appear to end at the poles of a magnet, but actually they continue on inside the magnet. They do however exit/enter the magnet at the poles.
"But Witchy," you may ask, "why are the lines so concentrated at the poles but then they spread out so much as they travel from one pole of the magnet to the other?" Excellent question my theoretical student XD.
This is I think the key point that was a bit of a eureka moment for me when I realized it a long time ago when I was studying this stuff: the magnetic field lines "want" to be as short as possible while also "wanting" to be as far apart as possible. And when I say want, it does actually behave a little bit like a desire, as the magnetic objects in this field will experience a magnetic force tryin gthe move the object to spread out the field lines and make them shorter.
Let's use this picture I grabbed from Wikipedia as an example:
the bar magnet creates a strong magnetic field at the poles, which means lots of magnetic field lines are squeezed closely together at the poles where they enter/exit the magnet. These lines don't want to be so tightly packed together, so they immediately start spreading out but also immediately start curving towards the opposite pole to try to keep the distance short. If you then try to bring the north pole of another bar magnet close to the north pole of this one, both have magnetic field lines coming out trying to get to their respective south poles, but now even more tightly packed together as you bring the magnets together. Since the magnetic field lines don't want to be so close together, both magnets experience a force pushing each other away so that the magnetic field lines aren't being pushed together so tight.
Similarly, if the south pole of one bar magnet is brought near the north pole of another, the magnetic field lines exiting the north pole of one want to go to the south pole, but the closest south pole is the south pole of the other magnet being brought close, so now the lines go through both magnets before looping back around:
However, between the closest poles of the two magnets, the lines are still concentrated but will try to spread out between the poles. Since the lines want to be as short as possible and don't want to spread out, the magnetic field exerts a force on the bar magnets pulling them together, since that would shorten the lines between the poles down to pretty much nothing.
Finally, a few of you may have been wondering what determines how much the magnetic field lines want to spread out vs shorten. These two tendencies are in opposition pretty much all the time, since spreading the lines out more requires making them longer. This is determined by something called the magnetic permeability which is a property of the materials that the field is passing through (even air or a vacuum). High permeability materials tend to concentrate the magnetic field lines more and allow them to get shorter, while low permeability materials tend to force the lines to spread out and lengthen. Examples of materials with high permeability are iron, cobalt, and other magnetic or ferromagnetic materials. Low permeability are pretty much anything that doesn't experience force in a magnetic field, so most things.
Post thumbnail attribution: (By Omegatron - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=640068)
Anyway I hope some of you enjoyed this rant or find the information here useful. I can talk about magnets all day so feel free to hit me up if you want, though my inbox will be overflowing for the next week I'm guessing.
Enjoy the Mega!
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family crap, manipulation, suicide. Really probably skip reading this one. This one's kinda messed up and I'm just here to vent I guess
I really want to cut my dad off. He's a manipulative fuck that hurts me to talk to. He royally fucked over my family and as a result none of my siblings talk to him anymore. It's his fault and he knows it and he's been trying to pick up the pieces ever since. He just called to try and guilt trip me into talking to my siblings and getting them to talk to him again. I told him no and that he should be glad I still talk to him and leave it at that.
But I don't want to talk to him anymore. It's so tiring. But the problem is I know for a fact that on some level he regrets what happened (though I'm not sure if he actually recognizes his own fault), and I'm also pretty sure he has thoughts of suicide. He thinks u by Kendrick Lamar is a healthy Christian response to being a sinner and that it's good to hate yourself. And he's told me twice that if it wasn't for God he would have killed himself already.
I had a friend in high school that killed himself, and I was strongly considering doing it myself in undergrad. It's such a sensitive subject for me. If I come across a post on here with a suicide CW I will not read it or it will probably ruin my entire day. If I cut my dad off and he kills himself because his last life line to what once was is now gone, it would destroy me.
I want to think about what's best for me, and I think what's best for me is to not have that trauma.
spoiler
My dad is also a manipulative abuser. He beat all of his kids, emotionally abused them and sexually abused some of us. I was his golden child, so I got it the least.
We had a falling out because during the child and family services apprehension of my little sisters, he was very mad that I took their side and wrote a letter of "support" about him where I was very honest about what he is like and what he has done. He never forgave me for anything I said. Around 4 years ago, he called me at midnight and said he was cutting me off. I got one message the next Christmas and my next birthday where he moaned that his "baby boy" doesn't want to talk to him anymore. I never had a chance to come out to him, it almost certainly would've gone badly because he's a Christian fundamentalist and a bigot. That call was the last time we ever talked or communicated, I've been healthier since the estrangement (that was his idea).
I wish he was the man I thought he was when I was a little kid.
My dad has been depressed and suicidal as well. But you can never take that on, what he chooses to do with respect to suicide is all on him. Don't take that burden, there's no need and it's not yours to take. My very first girlfriend ever, when I was in middle school, killed herself after I broke up with her. I was devastated, of course, and it took me a while to learn it wasn't my responsibility or my fault that it happened