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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Key Concepts
While the kids are playing with the experiments see if you can get them to notice these important ideas. When they can explain these concepts back to you (in their own words or with demonstrations), you’ll know that they’ve mastered the lesson.
Magnets
- Magnetic fields are created by electrons moving in the same direction. Electrons can have a “left” or “right” spin. If an atom has more electrons spinning in one direction than in the other, that atom has a magnetic field.
- If an object is filled with atoms that have an abundance of electrons spinning in the same direction, and if those atoms are lined up in the same direction, that object will have a magnetic force.
- A field is an area around an electrical, magnetic or gravitational source that will create a force on another electrical, magnetic or gravitational source that comes within the reach of the field.
- In fields, the closer something gets to the source of the field, the stronger the force of the field gets. This is called the inverse square law.
- A magnetic field must come from a north pole of a magnet and go to a south pole of a magnet (or atoms that have turned to the magnetic field.)
- All magnets have two poles. Magnets are called dipolar which means they have two poles. The two poles of a magnet are called north and south poles. The magnetic field comes from a north pole and goes to a south pole. Opposite poles will attract one another. Like poles will repel one another.
- Iron and a few other types of atoms will turn to align themselves with the magnetic field. Over time iron atoms will align themselves with the force of the magnetic field.
- The Earth has a huge magnetic field. The Earth has a weak magnetic force. The magnetic field comes from the moving electrons in the currents of the Earth’s molten core. The Earth has a north and a south magnetic pole which is different from the geographic north and south pole.
- Compasses turn with the force of the magnetic field.
Electromagnetism
- Electricity is moving electrons. Magnetism is caused by moving electrons. Electricity causes magnetism.
- Magnetic fields can cause electricity.
What’s Going On?
The scientific principles we’re going to cover were first discovered by a host of scientists in the 19th century, each working on the ideas from each other, most prominently James Maxwell. This is one of the most exciting areas of science, because it includes one of the most important scientific discoveries of all time: how electricity and magnetism are connected. Before this discovery, people thought of electricity and magnetism as two separate things. When scientists realized that not only were they linked together, but that one causes the other, that’s when the field of physics really took off.
Questions
When you’ve worked through most of the experiments ask your kids these questions and see how they do:
- How many poles do magnets have, and what are they?
- What happens when you bring two like poles together?
- How do I know which pole is which on a magnet?
- Is the magnetic force stronger or weaker the closer a magnet gets to another magnet?
- What kinds of materials are magnets made from?
- Name three objects that stick to a magnet.
- Name three that don’t stick to a magnet.
- What does a compass detect? How do you know when it’s detected it?
Answers:
- How many poles do magnets have, and what are they? Two. North and South poles.
- What happens when you bring two like poles together? They repel each other.
- How do I know which pole is which on a magnet? Put two magnets together and find the spot where they are repelling the strongest. The poles facing each other are the same. Or bring it close to a compass. If the magnet attracts the needle to north, then the magnet’s pole is the south pole.
- Is the magnetic force stronger or weaker the closer a magnet gets to another magnet? Stronger.
- What kinds of materials are magnets made from? Iron, nickel and cobalt.
- Name three objects that stick to a magnet. Paperclips, pipe cleaners, and staples.
- Name three that don’t stick to a magnet. US quarter, glass, plastic.
- What does a compass detect? How do you know when it’s detected it? The direction of a magnetic field. When the needle is deflected, the compass is in a magnetic field.
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I don’t believe anything would ever completely stop the magnet, but a material might slow it down even more. It would have to be something highly conductive of electricity (like copper or aluminum). The strength and size of the magnet as well as the thickness of the pipe would all be variables to consider.
One more question. About eddy currents…
Is there a material that, when a magnet is dropped though a pipe made of that material, the eddy currents will slow the magnet down so much that it seems to stop completely?
Scientists don’t really know what electrons look like. Theories include that they’re spherical, egg-shaped, or neither – they could be simply a field or force with no real form. Since they are so tiny and always in motion, humans haven’t been able to observe them with normal light. We can only see their effects right now.
That sounds right. Yes, it should work!
Will this wire work as well? Remington Industries 28SNSP.25 28 AWG Magnet Wire, Enameled Copper Wire, 4 oz., 0.0135″ Diameter, 507′ Length, Red
I didn’t think far enough ahead. I want it for early next week, and it won’t ship from Jameco until next Wednesday. But I can get this off Amazon by Friday. Doesn’t do me any good, though, if it won’t work for this unit.
Thanks!
In this video, you said that even if scientists had a really really really really really really really (okay you didn’t say “really” that many times) strong microscope, you still couldn’t see electrons because they’re moving so fast.
I had just watched some of your videos on relativity in astronomy, and as I watched this magnetism video, I wondered: If you could get an atom to move fast enough, and you had that really good microscope, could you take a picture of an electron right as it passed under the microscope, assuming you had really good timing with your camera? What would the electron look like?
When you break a bar magnet apart, you get two new (smaller) magnets like this:
N========S breaks into two pieces like this: N====S N====S
If you take one of those pieces and break it, you get: N====S becoming N==S N==S
And if you break those apart, you get: N==S becoming N=S N=S
You can keep doing this until you get to a single atom.
I noticed an error in the teleclass video that I just updated to make it more clear (around 43 minutes). You have to check where the magnet’s poles are first before you break the magnet. Try to use a magnet that has a pole at each end, not a pole at the top and bottom surfaces.
If you have a circular magnet, you have to look where the N and S are. Sometimes they are on the top and bottom surfaces (and then they’re not really poles), and other times they are on one side and the other, like cutting a donut into two C shapes, where each “C” is a N or S.
We have a question about breaking magnets. We don’t understand how the poles change? If this is the magnet +[ ]- and we break it in the middle, it would seem like now we would have +[ ]- and +[ ]- and they should still attract. We did break a magnet, and they obviously don’t attract, they repelled. But, we don’t understand how those original end poles change? Do all the poles just get mixed up and changed? You say in the video that they sprout new poles; does that mean that all poles change and reorient to the break points? We would love some more information on that if we could get it? Thanks. (Mom is helping me and we both want to know), Issachar
You’re asking a much more complicated question than I think you realize. Awesome job! Great scientists are always asking questions, no matter how smart they are or how old they are. 🙂
Let’s see if we can take it in two steps:
1. Electrons are influenced by magnetic fields, but it’s really hard to analyze how they do this. You usually cover this in college physics and it looks something like this:
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magint.html#c1
2. There are very specific places electrons can be in an atom. There’s no “in between” space – it’s either on track A or track B, for example. There’s no way it can be in between different “tracks” (energy levels, really). These locations are not changed when the atom is inside a magnetic field. (This might not be the case in very strong magnetic fields, like near magnetars, but as far as I can tell, this has never been tested.)
If electrons are drawn to a magnet, then could other things get closer to the nucleus than they normally would when the electrons are not being drawn to a magnet?