do u know how refrigerator magnets work?

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Jothaxe

Golden Member
Apr 5, 2001
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n0b7e,

In order to get an answer, maybe you could help by clarifying things a bit. I have seen two distinct types of things that you might label "magnets" stuck to various fridges.

1) The first is an actual refrigerator magnet that has a magnetic backing with a plastic or paper picture attached to the front. This device relies on magnetic attraction to stick to the fridge.

2) The second is a very thin pure plastic material that has a picture printed on it. It can even be translucent. This little guy has no adhesive, and yet sticks to the refrigerator due to electrostatic interactions. It is not fair to call this one a "magnet" but it might be possible to confuse it for one since it fulfills the same role as an actual magnet.


Can you please verify that you are talking about number one here? If so I will give you the explanation if nobody else has yet.
 

Wedesdo

Platinum Member
Jun 5, 2000
2,108
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noble: My answers are correct. There is no such thing as a cold oscillator... The ppl here are lying SOB's.

if you do not trust me, ask a random college physics professor or something (someone other than your current teacher.)

do not believe these other guys!!! esp. the cold oscillator BS..
 

ThisIsMatt

Banned
Aug 4, 2000
11,820
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<< Can you please verify that you are talking about number one here? If so I will give you the explanation if nobody else has yet. >>


Number 1. And they can be pretty much any thickness. It's just that they are plastic-esk....
 

Jothaxe

Golden Member
Apr 5, 2001
1,274
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<<

<< Can you please verify that you are talking about number one here? If so I will give you the explanation if nobody else has yet. >>


Number 1. And they can be pretty much any thickness. It's just that they are plastic-esk....
>>



In the case of number one, my answer is this:

It is untrue to say that refrigerator mangets will never stick when turned around. Some will, and some will not. And even those that dont stick to your fridge, may stick to something else, like a nice sheer iron face.

The reason these magnets do not stick as well when turned around is because there is a piece of nonmagnetic material on the front where the picture is printed. This material causes a gap between the magnetic material and the refrigerator, and this lessens the attraction between the magnet and the metal of the fridge.

There is no trick question here, there is no real mystery. I am sorry if you are dissapointed. So there is nothing &quot;inside&quot; a refridgerator magnet that is not &quot;indside&quot; a normal magnet... there are just a bunch of particles with uniformly aligned magnetic moments.

-jothaxe
 

ThisIsMatt

Banned
Aug 4, 2000
11,820
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Okay, I haven't had physics for about a year, and even then didn't emphasis magnatism, but extending what jothaxe wrote, doesn't the magnetic field decrease exponentially with the distance? That would factor into the non-magnetic reverse...
 

Harvey

Administrator<br>Elite Member
Oct 9, 1999
35,058
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ROTFLPIMP !!! :D :D :D

I have to hand it to n0b7e. He's got to know I was BS-ing as much as anyone else, and he got most of you believing he actually believed my explanation.

-- Allow me to give you Harvey Laws of Physics. They are very important laws that will get you some extra credit in class. You can call them n0b7e's Laws when you tell them:

1. Everything in the universe is made of two things, matter and doesn't matter.

2. Most of it doesn't matter.

3. The reason for time is to keep everything from happening at once.

I suspect you've noticed how well that last one works. I've found it's also good for telling the drummer where &quot;one&quot; is. ;)
 

Jothaxe

Golden Member
Apr 5, 2001
1,274
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<< He's got to know I was BS-ing as much as anyone else, and he got most of you believing he actually believed my explanation. >>



I sure hope you are right, but I disagree and think that he was actually buying what you said. Hence the confusion and anger...

Whether or not he bought it though, I enjoyed your very creative explanation involving &quot;cold osculators...&quot; very clever. ;)
 

Jothaxe

Golden Member
Apr 5, 2001
1,274
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<< Okay, I haven't had physics for about a year, and even then didn't emphasis magnatism, but extending what jothaxe wrote, doesn't the magnetic field decrease exponentially with the distance? That would factor into
the non-magnetic reverse...
>>



Specifically what I remember is that in the case of an ideal dipole, force goes down like 1/r^3 in the case that r>>L if L is the length of the dipole, or something like this...

But regardless of the actual factor, it does drop off quickly enough to account for the &quot;refrigerator magnet phenomenon.&quot; ;)
 

Shaka

Senior member
Oct 13, 1999
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Actually, I think magnetic force falls off proportionally to 1/(r^2) where r is the distance between the two bodies. So, when the magnet is directly touching the fridge, the magnetic force is greatest. If there is a piece of plastic between the magnet and the fridge, the magnetic attraction is less than before. Even though the plastic is thin, the magnet is weak and the force falls proportionally to 1/(r^2). I hope I am correct.
 

Jothaxe

Golden Member
Apr 5, 2001
1,274
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<< Actually, I think magnetic force falls off proportionally to 1/(r^2) where r is the distance between the two bodies. So, when the magnet is directly touching the fridge, the magnetic force is greatest. If there is a piece of plastic between the magnet and the fridge, the magnetic attraction is less than before. Even though the plastic is thin, the magnet is weak and the force falls proportionally to 1/(r^2). I hope I am correct. >>



I think that 1/r^2 is the case for the interaction between two magnetic dipoles. In this case we have only one, and it is inducing another dipole in the metal of the refigerator. For this situation I recall 1/r^3. Of course I havent had a course in EM for over 5 years, so I am very rusty and you may be right ;)
 

FrontlineWarrior

Diamond Member
Apr 19, 2000
4,905
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<< Harvery said
&quot;Actually, refrigerator magnets aren't magnets, at all. They're cold seeking osculators. When they sense cold on the other side of the refrigerator door, they suck real hard to try to get through it. Good thing refrigerator doors are made of steel. &quot;

This looks like a very credible answer, is this correct? Can someone add to this?

btw, can we please focus on *my* question.. please... whoever quizzed me, you can PM me and ill explain to you what magnetism is all about and why like poles repel and opposite poles attract, etc. etc... but for now, i'd really like an answer.
>>



LOL that sounded credible to you?
 

FrontlineWarrior

Diamond Member
Apr 19, 2000
4,905
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I have a similar question: WHY ARE REFRIGERATORS MAGNETIC TO BEGIN WITH???

ok I can guess what the answer is: It's not magnetic.

BUT, if that's the case, why is the outside of the refrigerator made out of metal and not like plastic? Wouldn't you want an insulator if you had a refrigerator instead of a conductor?
 

Jothaxe

Golden Member
Apr 5, 2001
1,274
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<< BUT, if that's the case, why is the outside of the refrigerator made out of metal and not like plastic? Wouldn't you want an insulator if you had a refrigerator instead of a conductor? >>



Plastic is brittle and doesnt hold up well as it ages, hence the metal. The refrigerator chassis is stuffed full of insulation anyways, so another fraction of an inch wont make much difference.
 

ThisIsMatt

Banned
Aug 4, 2000
11,820
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Thanks Jothaxe...I didn't pay attention to much E&amp;M, I only took the mechanics portion of the AP test (hey, I got a 4 :p). I was sorta right, right? ;)

<< two magnetic dipoles >>

ehh, so wouldn't that be 4?
 

Jothaxe

Golden Member
Apr 5, 2001
1,274
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0


<< I was sorta right, right? >>



Yeah ThisIsMatt you were right. You said exponentially, and 1/r^2 or 1/r^3 could definately qualify as that.
 

Maiora

Senior member
Oct 9, 1999
370
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0
Like Harvey's explanation of how the magnets work, here is an explanation of how the little light inside the reefer works! This applies to all light bulbs or darksuckers too!

For years the electrical utility companies have led the public to believe they were in business to supply electricity to the consumer, a service for which they charge a substantial rate. The recent accidental acquisition of secret records from a well known power company has led to a massive research campaign which positively explodes several myths and exposes the massive hoax which has been perpetrated upon the public by the power companies.

The most common hoax promoted the false concept that light bulbs emitted light; in actuality, these 'light' bulbs actually absorb DARK which is then transported back to the power generation stations via wire networks. A more descriptive name has now been coined; the new scientific name for the device is DARKSUCKER.

This newsletter introduces a brief synopsis of the darksucker theory, which proves the existence of dark and establishes the fact that dark has great mass, and further, that dark particle (the anti-photon) is the fastest known particle in the universe. Apparently, even the celebrated Dr. Albert Einstein did not suspect the truth.. that just as COLD is the absence of HEAT, LIGHT is actually the ABSENCE of DARK... scientists have now proven that light does not really exist!

The basis of the darksucker theory is that electric light bulbs suck dark. Take for example, the darksuckers in the room where you are right now. There is much less dark right next to the darksuckers than there is elsewhere, demonstrating their limited range. The larger the darksucker, the greater its capacity to suck dark. Darksuckers in a parking lot or on a football field have a much greater capacity than the ones in used in the home, for example.

It may come as a surprise to learn that darksuckers also operate on a celestial scale; witness the Sun. Our Sun makes use of dense dark, sucking it in from all the planets and intervening dark space. Naturally, the Sun is better able to suck dark from the planets which are situated closer to it, thus explaining why those planets appear brighter than do those which are far distant from the Sun.

Occassionally, the Sun actually oversucks; under those conditions, dark spots appear on the surface of the Sun. Scientists have long studied these 'sunspots' and are only recently beginning to realize that the dark spots represent leaks of high pressure dark because the Sun has oversucked dark to such an extent that some dark actually leaks back into space. This leakage of high pressure dark frequently causes problems with radio communications here on Earth due to collisions between the dark particles as they stream out into space at high velocity via the black 'holes' in the surface of the Sun.

As with all manmade devices, darksuckers have a finite lifetime caused by the fact that they are not 100% efficient at transmitting collected dark back to the power company via the wires from your home, causing dark to build up slowly within the device. Once they are full of accumulated dark, they can no longer suck. This condition can be observed by looking for the black spot on a full darksucker when it has reached maximum capacity of untransmitted dark... you have surely noticed that dark completely surrounds a full darksucker because it no longer has the capacity to suck any dark at all.

A candle is a primitive darksucker. A new candle has a white wick. You will notice that after the first use the wick turns black, representing all the dark which has been sucked into it. If you hold a pencil next to the wick of an operating candle, the tip will turn black because it got in the way of the dark flowing into the candle. It is of no use to plug a candle into an electrical outlet; it can only collect dark.. it has no transmission capabilities. Unfortunately, these primitive darksuckers have a very limited range and are hazardous to operate because of the intense heat produced.

There are also portable darksuckers called flashlights. The bulbs in these devices collect dark which is passed to a dark storage unit called a battery. When the dark storage unit is full, it must be either emptied (a process called 'recharging') or replaced before the portable darksucker can continue to operate. If you break open a battery, you will find dense black dark inside, evidence that it is actually a compact dark storage unit.

Maiora
 

StuckMojo

Golden Member
Oct 28, 1999
1,069
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the assertion that the thickness of the picture keeps the one side from attracting to the fridge doesn't seem likely.

if that is so, then why can i take a piece of plastic that is thicker than the picture (much thicker in fact), put it on the fridge, and use the magnet to hold it there?

there must be more to it than this. doesn't a magnet have directional properties? so that if you lined up the particles in the plastic correctly it could be more attractive on one side than the other?
 
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StuckMojo

Golden Member
Oct 28, 1999
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in fact, the &quot;picture thickness theory&quot; definately does not agree with the physical evidence.

try this experiment:

take 2 of these flat fridge magnets of the style that won't stick to the door if reversed.

turn one around so that the &quot;non-sticky&quot; side is against the fridge, then place the other one on top of it with the &quot;sticky&quot; side facing the fridge.

the second one will hold the first to the fridge. if the thickness of the picture were keeping it from sticking, than this experiment would fail.



you may say that the double thickness of magnet is enough to overcome the insulation effect of the picture...this may be true. a better experiment would be to peel the picture off the one side of the magnet and put it on the other side and see if it would cause the &quot;sticky&quot; sides to reverse.

hmm..in fact, just peeling the picture off and then seeing if it is equally &quot;sticky&quot; on both sides would probably do it :)
 

Jothaxe

Golden Member
Apr 5, 2001
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I agree with everything you have stated StuckMojo. I didnt think I had one to fiddle with last night, but I found one in my apartment, and I started playing with it.

There truly is a directional effect.

And yes, depending on how the particles are arranged it is certainly possible to have this sort of thing happen. The evidence? Try playing with a refrigerator magnet!!! ;););)

So although my posts seemed to make sense when I made them, they in fact have nothing to do with the refrigerator magnet effect. I am going to do some more experimentation later today and solve this damn conundrum.

When I do know the real answer (and I believe it hasnt yet been stated in this thread yet) I will start a new thread about it...

-jothaxe
 

Ameesh

Lifer
Apr 3, 2001
23,686
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for christ sake i cant belive that this post has gotten to 2 pages long of bs answers. to the newbie that asked, maybe you should take this class again, obviously you didnt get anything out of it the first time around.
 

Harvey

Administrator<br>Elite Member
Oct 9, 1999
35,058
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Maiora -- Thanks for letting folks know about the deep, dark secret of dark suckers. I was pledged to silence on the matter, but since you spilled the beans, and since it also relates to our present energy shortage problems, here's some other inportant information from one of the great scientific thinkers of our time, Dave Barry:

ASK DAVE: WHAT IS ELECTRICITY?
by Dave Barry

Today's scientific question is: What in the world is electricity? And where does it go after it leaves the toaster?

Here is a simple experiment that will teach you an important electrical lesson: On a cool, dry day, scuff your feet along a carpet, then reach your hand into a friend's mouth, and touch one of his dental fillings. Did you notice how your friend twitched violently and cried out in pain? This teaches us that electricity can be a very powerful force, but we must never use it to hurt others unless we need to learn an important electrical lesson. It also teaches us how an electrical circuit works. When you scuffed your feet, you picked up batches of &quot;electrons,&quot; which are very small objects that carpet manufacturers weave into carpets so they will attract dirt. The electrons travel through your bloodstream and collect in your finger, where they form a spark that leaps to your friend's filling, then travels down to his feet and back into the carpet, thus completing the circuit.

Amazing Electronic Fact: If you scuffed your feet long enough without touching anything, you would build up so many electrons that your finger would explode! But this is nothing to worry about, unless you have carpeting.

Although we modern persons tend to take our electric lights, radios, mixers, etc. for granted, hundreds of years ago people did not have any of these things, which is just as well because there was no place to plug them in. Then along came the first Electrical Pioneer, Benjamin Franklin, who flew a kite in a lightning storm and received a serious shock. This proved that lightning was powered by the same force as carpets, but it also damaged Franklin's brain so severely that he started speaking only in incomprehensible maxims, such as &quot;A penny saved is a penny earned.&quot; Eventually he had to be given a job running the post office.

After Franklin came a herd of Electrical Pioneers whose names have become part of our electrical terminology: Myron Volt, Mary Louise Amp, James Watt, Bob Transformer, etc. These pioneers conducted many important electrical experiments -- Among them, Galvani, who discovered (this is the truth) that when he attached two different kinds of metal to the leg of a frog, an electrical current developed, and the frog's leg kicked, even though it was no longer attached to the frog, which was dead anyway. Galvani's discovery led to enormous advances in the field of amphibian medicine. Today, skilled veterinary surgeons can take a frog that has been seriously injured or killed, implant pieces of metal in its muscles, and watch it hop back into the pond just like a normal frog, except for the fact that it sinks like a stone.

But the greatest Electrical Pioneer of them all was Thomas Edison, who was a brilliant inventor despite the fact that he had little formal education and lived in New Jersey. Edison's first major invention in 1877 was the phonograph, which could soon be found in thousands of American homes, where it basically sat until 1923, when the record was invented. But Edison's greatest achievement came in 1879 when he invented the electric company. Edison's design was a brilliant adaptation of the simple electric circuit: The electric company sends electricity through a wire to a customer, then immediately gets the electricity back through another wire, then (this is the brilliant part) sends it right back
to the customer again.

This means that an electric company can sell the customer the same batch of electricity thousands of times a day and never get caught, since very few customers take the time to examine their electricity closely. In fact, the last year any new electricity was generated in the United States was 1937; the electric companies have merely been re-selling it ever since, which is why they have so much free time to apply for rate increases.

Today, thanks to men like Edison and Franklin, and frogs like Galvani's, we receive almost unlimited benefits from electricity. For example, in the past decade, scientists developed the laser, an electronic appliance so powerful that it can vaporize a bulldozer 2000 yards away, yet so precise that doctors can use it to perform delicate operations on the human eyeball, provided they remember to change the power setting from &quot;Vaporize Bulldozer&quot; to &quot;Delicate.&quot;
 

n0b7e

Banned
May 30, 2001
243
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Damn yesterday i believe was my first day on this board, i attempted to use it to my advantage in getting a SIMPLE answer from maybe one out of a thousand. How the hell did it get this big? Can we just end this thread, i submitted my work already and any further &quot;answers&quot; are really irrelevant at this point, mainly because they were no good to begin with.

This board is fun tho, lotta participation.... yesterday i started this thread at night and left my outlook on to notify me if anyone replied, i swear like every 2-3 min another response... this sh!t was moving faster then a chatroom... thanks for everyone that participated you were no help except for the laughs and one or two people.
 

Jothaxe

Golden Member
Apr 5, 2001
1,274
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Hey n0b7e,

JSYK,

Sorry your thread got kinda out of hand yesterday. I dont think people appreciate how tough the problem is. Many people thought the question was a joke or something, but it is certainly a good mystery.

I talked to a couple of engineers, and a physics guy today at lunch, and none of them could explain it either. I am totally stumped myself.


What I have learned today is that there are two types of material inside even ignoring the plastic portion where the picture is printed: the back layer is magnetic, and the front layer is plastic of some sort that seems to be nonmagnetic. Its very hard to tell them apart, however because they are the same color.


And I am convinced that the thing is magnatized in some sort of alternating strip orientation, although I dont know enough to explain it.

Regardless, there is an orientation effect, and it is very subtle rather than obvious

*spelling edit*