Tag Archives: Magnets

Effortless DIY Electric Train

The relationship between electricity and magnetism is as old as space and time, but is a complicated one. As light propagates, electricity and magnetism flow in and out of each other, forever connected. This connection can allow for some pretty interesting phenomenons in physics.

DIY trainDue to induction, we can get the “train” to propel forward.  Induction is the act or process by which an electric or magnetic effect is produced in an electrical conductor or magnetizable body when it is exposed to the influence or variation of a field of force. This means that moving electricity induces magnetism, and moving magnets induces electricity.

DIY train 1Our “train” is composed of a battery and two strong magnets whose fields are repelling each others. It’s track is a long solenoid, or tightly coiled copper wire. The battery sends a current through the solenoid, which creates a magnetic field. That induced magnetic field then interacts with the magnets, repelling one magnet (pushing it) and attracting the other (pulling it). This push from one end and pull from the other creates a net forward motion (or if it is the exact opposite, then it will bounce out of the track due to a net backward motion).

If the two magnets are aligned with the battery such that their fields are attracted to one another, then there will be a net of zero movement. This is due to the induced magnetic field pulling the magnets in opposing directions. But, don’t take my word for it, give it a try for yourself!

DIY train gif

Written by: Mimi Garai

How Spinning Magnets Make the World Turn

We all know know what magnets are. At the very least, you’ve probably put one on the fridge. Magnets can come in all shapes and sizes, but they all work the same way. In simple terms, they have a north pole and a south pole. When two identical poles get close, they repel, and–of course–opposites attract.


Some of the many shapes, sizes, and types of magnets. Photos from coolmagnetman.

That said, many things about magnets are a lot more mysterious. Scientists explain these phenomena through something called a magnetic field, and this has some pretty wild and testable consequences. One of them is known as Faraday’s Law, which says that a changing magnetic field can generate electricity through a process known as electromagnetic induction. There isn’t a lot to be said about how this works; just as gravity pulls you down, moving magnets near wire will make electricity!


If this doesn’t seem all that interesting or important then just think for a moment about how much electricity we use. Then consider where that electricity comes from. Coal, wind, and nuclear power probably come to mind–but then how do we get the electricity out of those things? The answer is actually simple: magnets! Each of the major methods of making electricity really are just finding ways to spin a turbine which is connected to a magnet!

The amount of power that you get out of one of these generators depends on how many times the wire is wrapped around, how close it is to the magnet, and how strong the magnet is. This in turn makes the magnet harder to turn. If you look at a windmill, you will notice it has huge blades, allowing it to convert more wind into more power!


This wind farm in Palm Springs not too far from our campus employs this exact technology to generate electricity from the wind! Photo from best of the best tours!

DIY: Make a Magnetic Slime Monster!

Did you know that our planet is a giant magnet? It’s true! Without Earth’s magnetic field, compass navigation would be impossible. The field also shields us from cosmic radiation, directing most solar wind far around our planet. In space, large objects are generally too distant from each other to be noticeably pulled or pushed by the magnetic force between them. Here on the surface of the Earth, we have the advantage of being able to bring magnetic materials close together, which makes for some awesome experimental science!

It shouldn’t surprise anyone that iron sticks to magnets. Really, that’s all this demonstration is showing us. However, crazy, alien-like slime is a little cooler than slapping a magnet on a refrigerator. It’s lots of fun to make, and it’s not too difficult!

Mag Slime SetupHere is what you will need to make this at home:

  • A place where it is okay to make a mess
  • A mixing bowl, a small cup or beaker, and a spoon
  • A full container of school glue
  • Borax
  • Water
  • Iron filings and a neodymium magnet
  • Towels

Start by pouring the glue into the mixing bowl. Then, to get all of the glue out of the bottle, fill it with water. Shake it a lot to mix it up, and pour that into the bowl as well. Sprinkle some iron filings into the glue and water, keeping in mind that you can always add more later. It should look something like this:

Screen Shot 2016-04-04 at 1.47.25 PM

Next, fill your cup or beaker about halfway with water. Slowly add borax, stirring it in until it dissolves completely. Pour this solution into the bowl and start mixing. We started mixing with a fork, but then decided to get our hands dirty!

Slime Mixing gifStirring this mixture feels weird! It slowly clumps into squishy, almost cloth-like strips, but those strips don’t initially like to stay together. That’s okay! Keep squishing them around in the bowl. We found that in the end we had too much water or not enough patience (likely both) so we ditched the extra liquid, pulled all of the solidified bits together, and started molding them into a ball.

At this point, the magnet can be introduced. Note that neodymium magnets are very strong! They will grab anything metal tightly and suddenly. Usually, this only causes surprise, but it can lead to injury. Be careful, and keep this experiment away from all metal or otherwise magnetic objects.

Magnetic Slime gif

Due to the bits of iron in the slime, the magnet is attracted to it. Even cooler, if the magnet and slime are placed close together and left alone, the slime will be attracted to the magnet and cover it entirely! Note that the magnetic slime attack above is sped up a lot. The slime actually takes a few minutes to completely swallow the magnet.

If this isn’t happening with your slime, try adding more iron. We did this several times. Simply sprinkle in some more iron and continue mixing it in until you can’t tell where the iron was added. Don’t be afraid to experiment. After all, this is science!

Written By: Scott Alton, Caela Barry

DIY Electric Motor

Electric generators change mechanical energy into electrical energy. An electric motor does the opposite: HomopolarGifSmallit changes electrical energy into physical motion. This conversion is possible because of the Lorentz force.

Electricity is just the movement of electrons through a loop, called a circuit. Ever notice how magnets can repel or attract objects without touching them? When a circuit carries electrons near a magnet, the magnetic field pushes those electrons sideways.

The Lorentz force is strongest when the magnetic field and current-carrying wire are perpendicular to each other. Electric motors use this arrangement to turn electrical energy into mechanical motion efficiently. It’s easy to see for yourself, too! All you need is a magnetic field and a circuit that’s free to move. In today’s experiment, we’ll show the Lorentz force in action with a magnet, a battery, and a length of wire.

Labeled Parts

Start by setting the negative end of an AA battery on a strong magnet. Magnetic field, check; power source, check. Mold a length of wire into any shape that can balance on the positive end of the battery while also touching the magnet, completing a loop of conducting materials. Given a circuit to flow through, electrons begin to move, and voila! You’ve got a current flowing through a magnetic field. The current and the field are nearly perpendicular to each other where they intersect. The Lorentz force pushes the electrons, and the conductor they flow through, off to the side.

Shape the wire so that it can balance and spin on the positive terminal, and the electromagnetic push induces rotation for as long as the battery’s charge lasts. Electrical energy becomes physical motion. Congratulations– you’ve just created a motor!

Batman croppedSimple Cropped
Written By: Scott Alton, Caela Barry



Exploring Magnets with Ferrofluid

Magnets can do some pretty strange things. In first year physics classes, people are usually introduced to a mysterious thing called a magnetic field. These are invisible lines that help describe how magnets interact. This can make thinking about magnets rather intimidating, as it seems that they must be taken on faith. However, this doesn’t have to be the case!


Classic drawing of a magnetic field for a single magnet. Lines leave the north pole and enter the south pole. Credit: Tutorvista

Magnets interact with lots of things, but in particular are fond of iron. In fact, magnetism as we know it is known as ferromagnetism. In chemistry, “ferrous” means “containing iron”. With this in mind, carefully using tiny bits of iron known as iron filings, magnetic field lines can be seen!


Magnetic field viewed with iron filings. Credit: Henry Black, Practical Physics (1913)

See how the two pictures above line up? This particular picture is very accurate and mapped in painstaking detail. It tells us a lot about the magnet. Magnetic strength is indicated by the density of the magnetic field. In the image above, this shows us that–not surprisingly–the north and south poles of the magnet are the strongest!

We decided to take it one step further by using ferrofluid. By dissolving  this bits of iron in oil, the whole process becomes more dynamic–and a whole lot messier! If you are a follower of this blog, you probably realize this is pretty much exactly what we live for. You might expect when we bring our magnet next to it that it will just cover the whole magnet. However, that’s not quite what happens.


Magnet and ferrofluid. The magnet isn’t completely covered. There are small spikes where the magnetic field is.

Our magnet is a bit strange, it’s actually two iron spheres attached to two strong neodymium magnets. When arranged in this manner, the entire thing acts as one large magnet. This is sort of the inverse of an important magnetic property: All magnets have a north and a south pole. This means that if you were to cut a magnet in half, it would become two magnets, each with its own north and south pole. This essentially means that each magnet is a stack of smaller magnets, just like the one we are using! Lots of research has been dedicated to finding just a single pole, but these mysterious monopoles remain undiscovered.



Note that because ferrofluid is just iron filings and oil, it isn’t dangerous. It does leave a bit of a stain on skin, like oil can. In the animation above, you can see that our conglomeration of magnets has some cool features where the magnets connect. Using ferrofluid in this way makes magnets a bit less mystifying, and a lot more fun!


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