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magnet

A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, cobalt, etc. and attracts or repels other magnets.
A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field. An everyday example is a refrigerator magnet used to hold notes on a refrigerator door. Materials that can be magnetized, which are also the ones that are strongly attracted to a magnet, are called ferromagnetic (or ferrimagnetic). These include the elements iron, nickel and cobalt and their alloys, some alloys of rare-earth metals, and some naturally occurring minerals such as lodestone. Although ferromagnetic (and ferrimagnetic) materials are the only ones attracted to a magnet strongly enough to be commonly considered magnetic, all other substances respond weakly to a magnetic field, by one of several other types of magnetism.
Ferromagnetic materials can be divided into magnetically "soft" materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically "hard" materials, which do. Permanent magnets are made from "hard" ferromagnetic materials such as alnico and ferrite that are subjected to special processing in a strong magnetic field during manufacture to align their internal microcrystalline structure, making them very hard to demagnetize. To demagnetize a saturated magnet, a certain magnetic field must be applied, and this threshold depends on coercivity of the respective material. "Hard" materials have high coercivity, whereas "soft" materials have low coercivity. The overall strength of a magnet is measured by its magnetic moment or, alternatively, the total magnetic flux it produces. The local strength of magnetism in a material is measured by its magnetization.
An electromagnet is made from a coil of wire that acts as a magnet when an electric current passes through it but stops being a magnet when the current stops. Often, the coil is wrapped around a core of "soft" ferromagnetic material such as mild steel, which greatly enhances the magnetic field produced by the coil.

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  1. A

    Can I stick coat hanger up this pipe if I remove it from pump as magnet sticks to it

    Hi everyone.....thanks in advance for any help with this. Replaced some trv valves on downstairs radiators...( two down and 3 upsatirs) no heating now for 3 days. F and e tank empty at mo. I have a small magnet on pipe above pump and it sticks all the way from pump to the t junction...
  2. D

    Solenoid valve magnet

    Looking for a solenoid valve magnet for checking solenoids. I see Danfoss do one but......£45 !!!!! Is there a cheaper version available, or do folk just use a 'normal' magnet? 45 notes seems a bit steep.
  3. B

    Expired Worcester warranty and which magnet filter?

    Hi all. Great forum, We had a WB Greenstar 37CDI Combi Gas boiler fitted in 2011, at the time it came with 5 year warranty from Worcester. We have had it serviced yearly and manual stamped and touch wood has been trouble free. The warranty is now expired and just wondering what you would...
  4. finchy01

    Anyone recognise this magnet?

    Afternoon chaps. I've seen this before but never worked on one (I have spyro in my head) there are no isolation valves on it so I can't see how I can remove and clean it! The guy who put it in left no paperwork so I can't check. I've only used the Worcester and magnacleans before. Any advice...
  5. Lofty24

    Help what's the black thing?

    Been to look at a job but have never seen one of the black things, any help would be great. Thanks in advance
  6. Inverness

    Handheld Rotating Cleaning Magnet Roller

    Any suggestions for something to adgetate a sludged up radiator to help the circulation process for a magnetic filter to collect all the sludge from system. I know I can remove radiator form wall and shake it then flush out with garden hose. I'm thinking of another solution that I can adopt. Can...
  7. Super Mario

    Magnet for powerflush machine

    Where can I get the magnet that goes on the powerflush machine i think its orange ???
  8. Ted808

    Have you used an anton powerflush with orange magnet attachment..

    Hi there has anyone used the anton PF with magnet? ... is it ok? as opposed to the magnacleans plus a PF ? I want to expand my equipment and not sure if i should get the anton with the magnet attachment- 750 or the Magnaclease magnet 350 ....then i'd have to get a PF as well or continue to hire...
  9. H

    Spirotech Magnabooster 3

    I was wondering if anyone has any thoughts or fitted a Spirotrap mp3. Thanks.
  10. P

    Help Please

    Hi,I have narrowed down my central heating problems, I think, to a blocked f & e cold feed pipe,I have removed this pipe from the tank connected it to a tap with a pipe ,opened rad vents turned tap on , but nothing happenes The pipe is pretty much inaccessible, what can i do,Will a power...
  11. P

    Am I a bad customer / job magnet

    Hi guys I'm having a nightmare of late !!!! I started a bbu to combi change over last Tuesday the customer was hardwork from hour one I dug up the floor buryed the pipes except the gas all done right. came back Wednesday there was an atmosphere a. Bad one so carried on pipe work trvs ect ...
  12. K

    Killy bing trade deal : £50 off at magnet

    So guys sign up for a trade credit account at magnet and you get 50 quid off your first order over 100 quid. quite a good use of this is to sign up and order the stanley fatmax organisers which are normally 23 quid ish use this deal and you end up paying around 62 quid for 5 if i remember...
  13. R

    Boiler firing on and off all the time

    Hi i posted this in plumbing sorry for the repeat. I've an Ideal FF250, it fires up but then drops off and fires again straight away, I had a new pump fitted yesterday by the Gas board because it would only run on the top setting but its still doing the constant on and off, the GB man said he...
  14. S

    Cleaning Magnetic Filters

    Hi there I'm wondering if someone can advise me on the best way to clean the magnetic filter that's fitted on my sons central heating system. it's an easy thing to access, just by closing off aa inline valve and then removing the fitter for cleaning. I've done it once about a year ago and I...
  15. B

    Magnet on the oil line - Worcester Bosch 'Toaster'..

    Much to my despair, I have a WB Toaster in my house - it was fitted just before we bought the house. I HATE these boilers with a vengeance as its SOO hard to get the baffles out - once you have finally reached them (TOP TIP - replace roller access door chocolate screws with 20mm M6 stainless cap...
  16. P

    Just messing with my magnet again...

    Sticks to a 2p coin! Had heard they werent proper and probs made in China. Sent from my GT-I9100 using Tapatalk 2
  17. J

    Magnetic filters, Again!!

    I am confused by spyrotech filters, is it possible to remove the magnet? if you open it will the water automatically turn off or go all over the floor? seen 2 in last week and wasnt sure of any way to remove magnet so just opened up and flushed out the magnet. cant imagine this is too good though.
  18. G

    Stud and cable detector

    Anyone recommend a decent one? I had one and binned it because it gave false readings and was rubbish. I'd like a really good reliable one that works!
  19. J

    Magnets

    What magnets do people use for checking or blockages in central heating pipework?
  20. B

    fernox tf1

    well finished a full house install today,potterton gold 33 he(baxi duotec) and new rads,circuit etc bought a fernox tf1 baxi are promoting fernox kit and its being called a gold filter but its a tf1,i had been fitting magna cleans and have been impressed with them but the tf1 today decided to...
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