Tag Archives: Magnets

Electricity, Magnets, Motors & Batman


Building something and making it move can be intimidating, but it doesn’t have to be! While building an engine to power a car is a rather complicated task, some motors can be made with just a couple of simple supplies that you can pick up at the hardware store!

What you see in the video is called a Homopolar Motor. The name means that polarity of the motor never switches, which isn’t surprising considering that you’ve probably never see a battery’s ends suddenly switch places. The science that powers this motor is really cool and teaches a neat lesson about electricity and magnetism! To find out how it works, lets take a look at the setup in the video one more time:

Simple Cropped

First lets identify the parts. At the bottom is a very strong magnet, known as a neodymium magnet. This magnet produces a magnetic field–the thing that allows magnets to interact without touching one another. On top of that, there is a battery. Simple. Finally, there is the wire. The wire sits on the top of the positive terminal of the battery, and comes down and just barely touches the magnet on the bottom.

Labeled Parts

The wire is touching both the positive terminal and the neodymium magnet. The magnet is a conductor and is attached to the negative terminal of the battery. This means the two terminals are connected by a conductor and electricity starts to flow! Electricity is just the movement of charged particles. However, the electricity is flowing through an area with a magnetic field from the battery! There is a force known as the Lorentz Force that occurs whenever this situation arises. Mathematically, it looks like this:

Screen Shot 2015-04-08 at 8.35.23 AM

This looks like simple multiplication, but the letters have funny hats. This means they are vectors, which means that they include a direction. This makes multiplying them more complex as the product depends not only on the numbers, but how the directions relate to one another. While this can be confusing, the diagram below includes the current (or moving charges), the magnetic field, and the resulting force. See how it pushes the wire in a circle?

diagram

As you have seen in the video above, the picture can get more complicated than this. The wire can be in any shape you can dream up. As long as at least one end of the wire touches the magnet at the bottom, electricity will flow and the motor will move! As far as these motors are concerned, the science is pretty cool, but creativity is the real hero!

Batman cropped

The Magic of Ferrofluid

 

This is Ferrofluid. Invented at NASA, by Steve Papell in 1963, it is a liquid with bits of iron in it that will align along magnetic fields! Usually, it is kept inside of a container, often suspended in a clear liquid. Here, we let some of ours out to play!

The ferrofluid isn’t dangerous, although it does leave a nasty stain on skin and clothing, much like it is on our platter here, but it was well worth it!

Magnetic fields are an often mystifying concept, because of the inability to see it in normal circumstances, but with the addition of ferrofluid, it becomes much more obvious! In our setup here, the iron sphere is attached to two strong neodynium magnets, and becomes highly magnetized. The ferrofluid that made it to the sphere is condensed on the areas where the magnetic field is the strongest, allowing the magnetic field to become visible close to the magnet! We can now see something that is normally invisible!

While it seems exotic, ferrofluid is found in all kinds of everyday things, including speakers, transformers, and hard drives!

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