Magnetism and Magnet Science Projects
Before diving right into specific magnet science projects, we need to talk a bit about the general concept behind them first.
So ... whether you are looking at the aurora borealis, a compass, computer disc, cassette tape, high powered electromagnet or a simple refrigerator magnet, what could they all possibly have in common?
So what is it? How does it work? How can picking up paper clips have anything at all in common with the Northern lights ... and what magnet science projects can we find to demonstrate the basic concepts?
Well I'm glad you asked …
General knowledge of magnetism goes back many centuries. The Chinese are credited for inventing the first compass and through magnet science projects of their own, the Greeks are known for describing the properties of a special magnetic mineral called lodestone. But it wasn't until William Gilbert published his book "De Magnete" in the early 16th century that the science behind the observations actually got started.
In fact, before Gilbert questioned the accepted science of the day, magnetism was largely misunderstood, and explanations were quite creative. As two examples, Michael Fowler from the University of Virginia Physics Department notes, “…the first definite statement is by Thales of Miletus (about 585B.C.) who said loadstone attracts iron because it has a soul … “ He goes on to say that the first attempt at a scientific explanation was about 250 – 300 years later where, “ … tiny particles emanating from the loadstone sweep away the air and the consequent suction draws in the iron. …”
There were many mystical explanations as well, and it stayed that way for about another thousand years. Needless to say, many questions were left unanswered. By the way, his article is titled “Historical Beginnings of Theories of Electricity and Magnetism” and can be found at http://galileoandeinstein.physics.virginia.edu/more_stuff/E&M_Hist.html. Very interesting reading. I highly recommend it.
Enter William Gilbert ….
Gilbert conducted several magnet science projects and concluded that one way to magnetize a steel needle was to touch it with a loadstone. So how does that work? Is some mystical material being transferred from the loadstone to the needle? Keep reading ...
Gilbert also discovered a steel needle could be magnetized by cold drawing it (a way to make the needle) while pointing North, or by keeping the needle in a North/South direction for a long period of time. What’s up with that? We’ll soon see.
You see, Gilbert had a theory that the earth itself was one large magnet. The compass was well known by his time, so he used a piece of loadstone (the permanent magnet that exists naturally) to show a compass needle could be deflected by it, just like the earth does to make it point north. In fact, even though we haven’t gone into much detail about why magnetism works yet, this is still a good place to introduce the first magnet science project. I think you’ll see it clearly demonstrates the effect Gilbert himself showed several hundred years ago. The project is for very young students, but the concept is exactly the same.
So … back to the main question, what is magnetism? As is the case with many scientific concepts, it may be easier to describe what it does than what it is. I’ve used the Wikipedia definition for magnetism in the glossary, and at this point, it may indeed be hard to come up with a better one … but basically, it is a force between materials that either tries to push them away or draw them closer to each other all by itself. Let’s see if I can expand on that a bit, and then we'll get to some magnet science projects that demonstrate the concepts.
At the most fundamental level, magnetism is a force that comes from electrons, or electric charges in motion. Jumping right into it then … if that motion is due to electrons moving, we classify that as electromagnetism. If that motion is due to spinning, we have a permanent magnet. At the atomic level, we have both; Electrons orbit around the atom’s nucleus, and they also spin. The primary effect on the magnetic force comes from the electron spin.
Although theory allows for a single magnetic north or south, having a north and south pole, or a magnetic dipole is what we observe. So what does this have to do with a magnet we recognize? Well, going from the atom to a bar magnet, or why some materials do not appear to be magnetic at all is not as difficult a stretch as you might think …
First, although quantum mechanics may disagree, assume for a moment that electrons really do orbit the nucleus, and that they also spin. The spinning motion creates the stronger magnetic field, but the orbiting motion’s magnetic field is not ignored. What happens is that both are present, and one may tend to oppose the other. The total magnetic field is the sum of the two and the resulting field tends to have a north and south pole, hence the term dipole. As we discovered in our first magnet science project, just like the compass needle, if these small dipoles are then placed in the presence of a stronger magnetic field, they tend to align themselves with that field.
Next, take a bar of material, iron for example. It has billions of atoms (or tiny dipoles) in it. To make the bar, the iron was heated to a hot liquid and when it cooled, the atoms grouped together to form grains (like watching crystals grow) and the grains form boundaries between them and other grains. Inside each grain are atoms that are oriented in a similar (crystalline) structure, and that means many of the small atomic dipoles mentioned above will be pointing in the same direction. But just like in the atom, each individual grain may have a slightly different orientation. That means many of the magnetic fields at the grain level may cancel each other out as well. The net affect is that the final bar of iron might not even pick up a paper clip.
However, place that iron bar in a strong magnetic field for a period of time (or cold draw it as noted by Gilbert in a north-south direction), and those individual magnetic dipoles start aligning themselves with the external field. As will be seen in the next magnet science project, you will end up with a magnet.
Are all materials magnetic?
No, not all materials can be made into magnets. As the youngsters will find out in our next magnet science project, magnets do not attract all materials either. To find out why, it is important to know how well electrons in the atom itself are paired together. Since each electron has a magnetic field associated with it, and since all the field strengths are summed together (sort of like adding positive and negative numbers in arithmetic), atoms with most electrons paired together will cancel each other’s magnetic fields out. The result is no net magnetic field outside the atom and the material (plastic or wood for example) will not be magnetic.
And then there is magnetite (highly magnetic iron oxide). How do we explain that? Well, it was formed in such a way that the magnetic dipoles are not only aligned, but they are also frozen in place. As a result we end up with a permanent magnet. If you heat magnetite though, you can change that alignment and cause it to loose its magnetic properties as well.
So that brings us back to the question about what happens when you touch a material like steel with a permanent magnet (or a loadstone)? Pretty sure we can find a magnet science project to show the final result, but let’s see if we can use the above to answer it first …
Metals like steel (paper clips, etc) have electrons that are not paired. In other words, they have “free” electrons that can spin and orbit. That means they can generate magnetic fields that do not cancel out. Many become dipoles, or small magnets with a north and south pole and their field strengths are additive. On the larger scale, millions of these atoms are in the grains that make the steel and each grain can have an overall magnetic field as well. Grain fields may still cancel each other out to start with, but if the paper clip (for example) is placed in a strong outside magnetic field, or is touched with a permanent magnet, those “grain” fields tend to align with the permanent magnet’s field. As we should see in the next magnet science project, if the magnetic field is strong enough, or the steel stays in contact with the magnet long enough, the steel’s grain fields can get “set” in place. The final result is that the steel becomes magnetized (acts like a permanent magnet) and the paper clip will now pick up another paperclip without needing to touch the permanent magnet anymore. But don’t strike the new magnet with a hammer, (or heat it up too much), or the grains may go back to their original state and the paperclip looses its ability to act like a magnet anymore. Take a look at this magnet science project. It shows how we can make a magnet from everyday items around us.
Electromagnets and electro magnet science projects are simply fascinating, not to mention almost endless. What we are really talking about here is a fine line between electricity and magnetism. They are different, but very much related. So much so, in fact, that one can be used to create the other!
As noted above, moving electrons create a magnetic field. But isn’t an electric current just a bunch of electrons moving through a wire? If so, shouldn’t we be able to create a magnetic field just by plugging in our reading lamp? Absolutely. In fact, if you connect the positive and negative terminals of a battery together with a wire (in a magnet science project of your own), and wrap the fingers of your right hand around the wire so your thumb points away from the positive terminal, your finger tips will point in the direction of the magnetic field created by the movement of those electrons through the wire.
Likewise, if in yet another magnet science project, you make a coil of wire and connect the two ends to a small light bulb, then passed a strong magnet through the center of that stationary coil of wire, the magnetic field would cause electrons in the wire to move as well. In other words, you could “induce” a current flow in the wire. If the magnet was strong enough, and you moved it through the wire fast enough, you could make the light bulb shine without having to hook it up to a battery. For you old timers out there, this is the principle that was used to start heavy machinery “back in the day” (mag-starter) and is also the same concept that allowed the original bell telephones to ring the operator. Ok, the same principle is used to make modern-day generators as well.
So what does all that have to do with electromagnetism? Everything! This is what electro-magnetism is. One creates the other. In fact, all we have to do to make a magnet we can turn on and off at will is to pick the right material as a metal “core”, wrap a wire around it, hook the ends to our power source and turn it on! If we want to drop whatever material we picked up with the electromagnet, all we have to do is turn off the power. Now that is useful .. and certainly worthy of a magnet science project all it's own!
So … if we wrap a wire around, say an iron rod and hooked the ends of the wires to an adjustable power source, we could even control the strength of the magnet by controlling how much current flowed through the wire. Strong current = strong magnet. In fact, just like you see on TV, these magnets can be strong enough to pick up an entire car!
But picking up a car is not necessary to demonstrate the concept. On a smaller scale, take a look at electro-magnet science project. It shows how we can make a pretty strong electromagnet from everyday items as well.
And What If We Combine The Two?
Now we're talking! Take a look at the DIY Electric Train project to see how much fun we can have if we turn a little electricity into a magnetic field (instead of the other way around in the electromagnet) and then add actual magnets to the mix? Go ahead ... take a look!
... and with that I must stop for the day. As noted on the home page, this will be a growing site, so please check back frequently. I'll include more magnet science projects very soon!
More Magnet Science Projects coming soon!
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