Fading magnetism?

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  1. No, I don't mean losing the love for a bag ;) ... but has anyone of you noticed that the magnetic closures of older Mulberries seem to get weaker? When fondling new bags on the shelves, I realized the buttons almost jump on each other while I have to fiddle quite a bit to close mine. Or do they just use stronger magnets now? And a question for the scientists here: is is possible to strengthen the magnetism - e.g. by rubbing a piece of metal or another magnet on them?? I'm useless when it comes to science, but I'm sure you can tell that ...
     
  2. Ooo,now this is interesting,mmmm,I have the Rox,3-ish years old,and the mags seem fine,and compared to the new aqua seem ok too, but that said I don't use the same bag all the time? Mmm,and I think you can recharge mags,by rubbing them with another magnet,I'm sure I read that someplace?? Not to do with bags,but some other thing when I was a kid or something???

    I did get a Babington,and the sa explained the mags were'nt great,and she was right,I'm not sure,maybe the magnets are'nt polarised properly??? I swapped it for an Annie at any rate,mmm,maybe I should have had an experimental session with it??
     
  3. Oh yes, I knew this is another case for scientist chaz!

    :tup:
     
  4. ^^^^^^^^ Hahhaa!! You know me too well!! I think I'll have a wander around on google and see what I can turn up on this one,I'm sure there will be some boffin site that deals with little anomalies like this.
     
  5. [edit] My 4yo son wants to know 'How do they make magnets'?

    So guys, how do they make magnets? Im assuming he's interested in the garden variety, solid stick things to your fridge variety. Thanks for any simple explainations..
    Do you want to know how to take raw materials (like a ceramic powder) and turn them into a bar and then magnetize it, or do you just want to know how to take a material that isn't normally a magnet (like scissors) and then give it its own magnetic field? For a four year old, I'd go with the latter, the explanation is simpler and is probably what he's trying to ask. You can do an experiment with him (actually, you'll need to do it with him for safety) to turn something into a magnet: Buy a neodymium magnet (also known as a rare earth magnet). They're available from loads of online retailers and from some stores. Take the magnet and stick it to the metal part of the scissors close to the handle. Be very careful when you do this--rare earth magnets are extremely strong. Do not let your child play with them. Once you've got it stuck to the scissors, then have your son help you slide the magnet all the way down the scissors and all the way off. Then reattach the magnet close to the handle, have your son help you slide it off, and repeat this over and over. After like 20 or so slides down the magnet, you can use the scissors to pick up a single staple or something small like that. An easy explanation could go something like this: Imagine you're running a comb through hair. As you run the comb through more and more times, all of the hairs get more and more lined up with each other, until all of the hairs are pointing in the same direction. You have to run the comb through the hair, and then take the comb out and go back to where you started, and then run it through again. In the scissors, there are lots of really tiny magnets all pointing in different directions. When you drag the big magnet along the length of the scissors, you're dragging all of the little magnets inside the scissors into rows. After a while, they're all pointed in the same direction (just like the hairs with the comb), so you've made all of the little magnets behave like one big magnet!Pkeck 05:28, 3 January 2006 (UTC) Yes, that's a valid demonstration, but it's not really "how they make magnets". Unfortunately, the real process is not something you can easily do in your kitchen. Fridge magnets and the like are made from powdered ceramic material which is either sintered (welded by applying high pressure) into a rigid block, or embedded in flexible plastic. At this point, the object is not yet a magnet. It is then heated above its Curie temperature, placed inside the magnetic field of a much larger magnet, and cooled. When it is cold, it retains the magnetic field of the larger magnet. This is the adult version. I don't know what sort of words a four-year old boy understands, so I leave the translation up to you! --Heron 11:00, 18 February 2006 (UTC) A simple version you could try: a big magnet it made up of tiny particles, and when aligned in the same direction, they form a magnet-you can do a demonstration with small bits of paper. have N and S on each end and show how they become aligned form scrambled. Ursper 20:13, 29 April 2007 (UTC)

    [edit] Far field of a magnet
     
  6. [edit] Permanent magnets

    I'd want to know, in these permanent magnets, is the magnetic field constant, or will it drain when used? And if so, will it regenerate? Take the average ABC hanging on your fridge. Will they come down due to weakened magnetic properties? Naturally one would assume that eventually they should come down, due to energy transformation. But I have yet to see a magnet fall down/stop beeing magnetic. So basically, is there any info on energy in permanent magnets?
    A magnet does not lose energy by being used, and will stay on your fridge forever unless something happens (such as heating, shock or a strong external magnetic field) to demagnetise it. There is no "energy transformation", as you put it. The magnet is not using any energy ("doing work") to stay stuck to the fridge, because work = force x distance moved, and nothing is moving. The only energy transfer occurs when you stick the magnet to your fridge in the first place. As the two objects approach, some of the magnet's field goes into the metal of the fridge, resulting in a decrease in the field's energy (technically speaking, you are decreasing the reluctance of the magnetic circuit). The energy released from the magnetic field goes into pulling on your arm muscles, which turn it into heat. If you pull the magnet off the fridge, your muscles have to put that same amount of energy back into the field. You can do this as many times as you like without draining the magnet, because the energy is coming from you, not from the magnet. There is some energy stored in the magnetic field of a permanent magnet, equal to the energy that was put in to magnetise it in the first place. This PDF is a good reference on the subject. This other PDF is good at explaining how permanent magnets work. Both of them discuss how to calculate the energy stored. --Heron 19:53, 27 July 2005 (UTC)
    [edit] Iron filings
     
  7. Magnetization and demagnetization

    Ferromagnetic materials can be magnetized in the following ways:
    • Placing the item in an external magnetic field will result in the item retaining some of the magnetism on removal. Vibration has been shown to increase the effect. Ferrous materials aligned with the earth's magnetic field and which are subject to vibration (e.g. frame of a conveyor) have been shown to acquire significant residual magnetism. A magnetic field much stronger than the earth's can be generated inside a solenoid by passing direct current through it.
    • Stroking - An existing magnet is moved from one end of the item to the other repeatedly in the same direction.
    • Placing a steel bar in a magnetic field, then heating it to a high temperature and then finally hammering it as it cools. This can be done by laying the magnet in a North-South direction in the Earth's magnetic field. In this case, the magnet is not very strong but the effect is permanent.
    Permanent magnets can be demagnetized in the following ways:
    • Heating a magnet past its Curie point will destroy the long range ordering.
    • Contact through stroking one magnet with another in random fashion will demagnetize the magnet being stroked, in some cases; some materials have a very high coercive field and cannot be demagnetized with other permanent magnets.
    • Hammering or jarring will destroy the long range ordering within the magnet.
    • A magnet being placed in a solenoid which has an alternating current being passed through it will have its long range ordering disrupted, in much the same way that direct current can cause ordering.
    In an electromagnet which uses a soft iron core, ceasing the flow of current will eliminate the magnetic field. However, a slight field may remain in the core material as a result of hysteresis.

    Types of permanent magnets

    I think this one covers the topic best.And would you belive,I have just read a couple of posts on these topics,and they do get a bit pissy with each other!!! Very funny!!
     
  8. Wow, that's exhaustive - isn't it wonderful what topics people can spend their time discussing? The heating thing sounds like a "don't try this at home, and not with a bag attached" for me, but I might try hanging the straps from my fridge. Normally my fridge wall is covered by a wooden board, but that has fallen down, and I haven't yet fixed it, so that might be the chance for an experiment.
    :smile:
     
  9. Okay, my husband is a physicist and I told him to give a simple answer - which is a hard a thing for a physicist! He says that it is possible to remagnetize a magnet - for example by connecting a stronger magnet to the weaker one for several days. You should connect them in the "usual" way, i.e. by observing the attraction from a south to a north pole or vice versa. My husband always reminds me to keep the magnets of my handbags closed most of the time. Otherwise the magnets will weaken over time because the field lines spread out too much. Falling to the ground or hard blows might also disturb magnets. Hope this helps!
     
  10. Mmmm,I found it very interesting too,I might just have to do a lil experimenting..................could be worth it for future reference!!!
     
  11. Monsti!!!! Thats fabulous!!! Thank you so much!! And your hubby too!!!
     
  12. Can't you just rub some Viagra on it??? Sorry, just couldn't resist! Have such a dirty mind that's always in the gutter!:lol::upsidedown::lol:
     
  13. Hahahaha!!!!^^^^^^^^^^^^
     
  14. Great thread! Here I can ask my question :smile: So, I bought my soho and there is magnet behind that gold thing.. and I remembered that one day when my mom carried a fridge magned (or something like that) in her purse - her credit cards didn't work anymore! Those magneds affect that way to credit cards etc..

    So now I'm a little consern about my cards because I don't like to carrie cash around an prefer cards. How careful do I need to be with my wallet not to go too close of this magnet? :s
     
  15. I've never had any problems with the magnets on my bags wiping my cards,I think if your Mum had a magnet in such close proximity for a while,thats what must have done it.Mine are usually in my wallet,and then that floats around in the bottom of my bag,so quite far away from the magnets to be any real problem I guess??