Special Science Teleclass: Magnetism

Monday October 20, 2014

This is a recording of a recent live teleclass I did with thousands of kids from all over the world. I’ve included it here so you can participate and learn, too!


Discover how to detect magnetic fields, learn about the Earth’s 8 magnetic poles, and uncover the mysterious link between electricity and magnetism that marks one of the biggest discoveries of all science…ever.


Materials:


  • Box of paperclips
  • Two magnets (make sure one of them ceramic because we’re going to break it)
  • Compass
  • Hammer
  • Nail
  • Sandpaper or nail file
  • D cell battery
  • Rubber band
  • Magnet Wire

Optional Materials if you want to make the Magnetic Rocket Ball Launcher:Four ½” (12mm) neodymium magnets


  • Nine ½” (12 mm) ball bearings
  • Toilet paper tube or paper towel tube
  • Ruler with groove down the middle
  • Eight strong rubber bands
  • Scissors
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Which way is North?

Sunday April 4, 2010

I can still remember in 2nd grade science class wondering about this idea. And I still remember how baffled my teacher was when I asked her this question: “Doesn’t the north tip of a compass needle point to the south pole?” Think about this – if you hold up a magnet by a string, just like the needle of a compass, does the north end of the magnet line up with the north or south pole of the earth?


If you remember about magnets, you know that opposite attract. So the north tip of the compass will line up with the Earth’s SOUTH pole. So compasses are upside-down! Here’s an activity you can do right now…
Materials:


  • magnet
  • compass
  • string
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Bouncing Magnets

Sunday April 4, 2010

Want to see a really neat way to get magnetic fields to interact with each other? While levitating objects is hard, bouncing them in invisible magnetic fields is easy. In this video, you’ll see how you can take two, three, or even four magnets and have them perform for you.


Are you ready?


Materials:


  • 3 identical magnets
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Magnetic Fields

Sunday April 4, 2010

This is a quick and simple experiment to answer the question of magnetic field strength: Do four magnets have a stronger magnetic pull than one? You’ll find the answer quite surprising… which is: it depends. Here’s what you need to do to see for yourself:


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Magnetic Sensors

Sunday April 4, 2010

reed-switchWouldn’t it be cool to have an alarm sound each time someone opened your door, lunch box, or secret drawer? It’s easy when you use a reed switch in your circuit! All you need to do it substitute this sensor for the trip wire and you’ll have a magnetic burglar alarm.


The first thing you need to do is get your reed switch out, because we have to tear into it in order to get the part we need.  Here’s what you need:


Materials:


  • reed switch
  • magnet
  • LED
  • AA case
  • 2 alligator wires
  • 2 AA batteries
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Magnet Boats

Sunday April 4, 2010

We took our first step into the strange world of magnetism when we played with magnetizing a nail. We learned that magnets do what they do because of the behavior of electrons. When a bunch of those crazy little guys get going in the same direction they create a magnetic field. So what’s a magnetic field, you ask? That’s what this experiment is all about.


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Simple Magnet Experiments

Sunday April 4, 2010

magnet-nailLet’s play around with the idea of lining up all the mini-magnets inside an object to magnetize it. You’ll need a steel nail (steel is a combination of iron and carbon), a magnet (the stronger the better), and a few paper clips. Here’s what you do:


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Magnetic Grape

Sunday April 4, 2010

Every atom has electrons, and electrons both go around the core and also spin. Depending on how they spin and how much energy the atom has will determine what kind of magnetic properties your atom will have.


Iron is ferromagnetic, which means it’s attracted to both poles of a magnet – bring a nail close to any part of a magnet and you’ll always feel a pull, never a push.


Water (which is what your grape is mostly made up of) is diamagnetic. Things that are diamagnetic are repelled by both poles of a magnet, although very weakly (almost a million times weaker than ferromagnetic).


Paramagnetic materials (like a soda can, hydrogen, lithium, and liquid oxygen) is very weakly attracted to both magnetic poles, but it’s not noticeable until you bring the temperature of the soda can WAY down.


Here’s a nifty way to see diamagnetic properties in a material. Ready?


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Ferrofluid

Friday July 1, 2011

A ferrofluid becomes strongly magnetized when placed in a magnetic field. This liquid is made up of very tiny (10 nanometers or less) particles coated with anti-clumping surfactants and then mixed with water (or solvents). These particles don’t “settle out” but rather remain suspended in the fluid.


The particles themselves are made up of either magnetite, hematite or iron-type substance.


Ferrofluids don’t stay magnetized when you remove the magnetic field, which makes them “super-paramagnets” rather than ferromagnets. Ferrofluids also lose their magnetic properties at and above  their Curie temperature points.


Ferrofluids are what scientists call “colloidal suspensions”, which means that the substance has properties of both solid metal and liquid water (or oil), and it can change phase easily between the two. (We as show you this in the video below.) Because ferrofluids can change phases when a magnetic field is applied, you’ll find ferrofluids used as seals, lubricants, and many other engineering-related uses.


Here’s a video on toner cartridges and how to make your own homemade ferrofluid. It’s a bit longer than our usual video, but we thought you’d enjoy the extra content.


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Eddy Currents and Magnetic Brakes

Sunday April 4, 2010

Eddy currents defy gravity and let you float a magnet in midair. Think of eddy currents as brakes for magnets. Roller coasters use them to slow down fast-moving cars on tracks and in free-fall elevator-type rides.


Here’s what you need to do this activity:


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