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Magnetism
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Sixth segment of NASA Sci Files The Case of the Technical Knockoutexplaining how gases glow different colors when electrons pass through them and discusses the different magnetic properties. In this segment students conduct an experiment to find out how voltage and magnetism are related.
Be sure to look for the answers to the following questions.
00:00:00
What is solar wind?
00:00:04
What does voltage measure?
00:00:05
Name the layers of the atmosphere.
00:00:06
Describe a convection cell on the sun.
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When you see this icon, the answer is near.
00:00:08
What about a nice bag of beef jerky?
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Don't you think after a long day of hiking and geocaching, you might want some beef jerky
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or something of substance?
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Sorry, Jacob.
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Nothing perishable.
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We need to put things into our cache that are fun and interesting as treasure, not a
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meal.
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Well, I'm running out of ideas.
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What do you have so far?
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I had lots of food items.
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Signal flares might be hazardous in the forest.
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Cache or a gift certificate?
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Why don't we just put travel bugs in our caches?
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Hi, RJ.
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What are travel bugs?
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They sure don't sound like treasure.
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My dad got me this one on the internet.
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It doesn't look like a bug.
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It's not a real bug.
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Each travel bug has its own unique tracking number.
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So when someone finds our cache, they take out the travel bug and place it into a different
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location.
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Then they look up on the internet the travel bug tracking number and type in the new location
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of the cache that they placed it in.
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So your travel bug could travel to geocaches all around town?
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Actually, it can travel the world.
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How would that work?
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Let's say we place a travel bug in our cache and then someone from New York is geocaching
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in our area.
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They take the bug back to New York and place it in a cache in their city.
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Someone from London visits New York to geocache and then they take it with them back to London.
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What a cool idea.
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We have to get some travel bugs.
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We have one, but we can get some more.
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Our travel bugs could see the world.
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How cool is that?
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Wait a minute.
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We're getting ahead of ourselves.
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I know working on our caches is part of the assignment, but we still haven't solved our
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problem.
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I was reading Tony's report on electricity and he said we need to learn more about magnetism.
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I think Ula and Neena are meeting with Dr. D again.
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Hopefully we should get their report soon.
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For great ideas on creating reports, visit the Treehouse and the NASA Sci-Files website.
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I'm really looking forward to the Northern Lights Festival tonight and hopefully seeing
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some auroras with the kids club members.
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Andanus is the perfect spot for viewing auroras because it is located directly under the auroral
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oval.
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Of course, Neena and Ula are also investigating magnetism for the Treehouse detectives.
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This is a good place to start.
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We know that magnets have a North Pole and a South Pole.
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And the two North Poles repel and the North and the South Pole attract each other.
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Very good.
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Let's demonstrate that by having you push light poles of these two magnets together.
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Oi, they're really strong.
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Let's take a look at the magnetic field of this permanent bar magnet.
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That's impressive.
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Notice how the South Pole, or white part of this compass needle, points to the North Pole
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of the bar magnet.
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So if a compass always points to where the Earth's North Pole, that must mean that the
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Earth is a big magnet with a magnetic pole up north.
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You're right.
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This magnetic field looks very similar to the field of this bar magnet.
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I heard that the Chinese used a lodestone to produce their first compass.
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Historians think so.
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Here is a piece of lodestone, a naturally magnetic rock.
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If I float it on this phone, it will point north.
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Doesn't magnetism have something to do with electricity?
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Yes it does.
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Magnetic fields are produced by moving charges.
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Let's make an electromagnet by having an electric current flow through this wire which is wrapped
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around an iron bar.
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This field looks just like the bar magnets.
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Except when I turn off the current of an electromagnet, the magnetic field disappears.
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So is the Earth like a giant electromagnet or like a permanent magnet?
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Well, the Earth has an outer core made of molten iron that is constantly in motion.
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A process called the dynamo effect creates huge currents of electricity in the iron which
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produces a giant electromagnet.
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In like manner, the Earth's magnetic field deflects the protons and electrons of the
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solar wind which the Sun is throwing at the Earth at hundreds of kilometers per second.
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Ah, I get it.
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Didn't a Norwegian scientist named Christian Birkland investigate the solar winds and auroras?
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That's right.
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He used a magnetized sphere called a torella to represent the Earth and he fired an electron
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beam at it to simulate the solar wind.
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What did he discover?
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He found that the electron beam did cause the gases in the chamber to glow like an aurora
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and the magnetic field guided the electrons like beads in a string to the poles of the
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torella.
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And we know that auroras occur on Earth near its poles.
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Very good.
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Here is an example of how high energy electrons can cause a gas to glow.
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This is a tube of helium gas hooked up to a high voltage power supply.
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The tube is glowing pink.
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Each gas gives off its own special color.
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Here is neon gas which looks orange.
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Just like the lights at restaurants.
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That's right.
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Auroras produce greens, blues and reds when electrons collide with oxygen and nitrogen
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atoms hundreds of kilometers above the Earth's surface.
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Auroras certainly don't look that high.
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Dr. Deek, wasn't there a problem with Birkland's theory?
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Yes, he had the misconception that it was electrons coming directly from the Sun that
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caused the aurora.
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Well, where do they come from?
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They do come in part from the Sun.
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The solar wind compresses the magnetic field on the day side of the Earth and stretches
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it into a long tail called the magnetotail on the night side.
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Electrons from the solar wind flow around the day side and into the magnetosphere at
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the tail.
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Then what happens?
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The electrons in the magnetotail are then pulled back down toward the poles at increasingly
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high speeds by electric forces.
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These are called Birkland currents.
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And when they collide with the gases in the atmosphere near the poles, we have an aurora.
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Exactly.
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But to really understand auroras, you must first learn more about activity on the Sun
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like sunspots and flares.
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Thanks, Dr. Deek.
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Let's get our report on magnetism ready for the Trias detectives.
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Maybe they can help us investigate the Sun.
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Okay, let's fire up the computer.
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I'm ready to talk magnetism with our friends at the Andenes Barnard School in Norway.
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It's not every day we have a transatlantic experiment.
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I would love to visit Norway and see the culture close up.
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Well, how about the next best thing?
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We're ready to talk to the NASA Sci-Files Kids Club members in Andenes.
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Perfect.
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They should be ready just about now.
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Hi, I'm Jacob here with Bianca.
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We understand you're doing an experiment on magnetism.
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Hi, I'm Ingrid.
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And I'm Alexander.
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Hi.
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Dr. Deek told us that you're working on an electromagnet experiment.
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Can you tell us about it?
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Sure.
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Our electromagnet is a wire wrapped around an iron nail attached to a battery.
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We wanted to find out how the strength of the electromagnet changes when we increase
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the voltage.
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And we increase the voltage by using more batteries.
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We learned in science class that a battery is like an electrical pump that pushes electrons
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through a circuit.
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The voltage measures the push.
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And the flow of electrons through the wire is called a current.
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We learned that too.
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We also learned that as the voltage is increased, the current in the wire will increase.
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So we hypothesized that if we increase the voltage and get more current, then the strength
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of the electromagnet will also increase.
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Sounds like excellent reasoning.
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We began by wrapping wire around the nail 300 times.
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Next we placed a 1.5 volt battery in the battery pack.
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We then connected one end of the wire to the positive battery terminal.
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And to complete the circuit, we connected the other end to the negative terminal.
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You won't get any current or flow of electrons unless you have a complete circuit.
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That's right.
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And the current in the wire then causes the nail to become a magnet.
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To test the strength of the magnet, we placed it in a cup of paperclips.
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I would think that the stronger the magnet, the more paperclips it would pick up.
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We agree.
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In our first trial, we picked up six paperclips.
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We know in an experiment it is important to do multiple trials and then find the average.
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What was your average?
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The class average was eight paperclips with 1.5 volt battery.
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To continue to test our hypothesis, we added another 1.5 volt battery, increasing the voltage
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to three volts.
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The average was 14 paperclips with two batteries.
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Wow!
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You doubled the voltage and almost doubled the number of paperclips.
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We continue by adding a third battery.
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With 4.5 volts, we averaged 21 paperclips.
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Four batteries, or six volts, picked up an average of 30 paperclips.
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Congratulations!
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It looks like you've proved your hypothesis.
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That's right.
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We graphed the results as well.
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A graph clearly shows that the strength of the magnet increases as the voltage increases.
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Our teacher, Ulla, also told us that the Earth's magnetic field is very similar to our electromagnet,
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except the current in the Earth is a billion times the current in our circuit.
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That's incredible!
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I was wondering, does the number of times you wrap the wire around the nail make a difference?
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We think so, but that is what we're going to test next.
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Great!
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Be sure to send us your results.
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We will.
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Goodbye.
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From Andenes Børneskole, Norway.
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I can't believe all the cool experiments we've seen.
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Anthony, Dr. Bagnall, Dr. Dean, the Kids Club members, and now the Kids Club in Norway.
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Clearly there's a connection between electricity and magnetism, but I'm not sure how.
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I'm still sorting through Ulla and Nina's report on auroras.
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Dr. D also said that before we can fully understand auroras, we need to learn more about the Sun.
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I completely forgot about the Sun.
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How are we going to learn more about the Sun?
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Don't worry.
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I've done some research on the Internet, and NASA does lots of research on the Sun.
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Of course!
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The answer is NASA.
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Let's go.
00:10:09
Slow down.
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Ulla and Nina also reported a teleconference that they had with North Shore Christian Academy in Everett, Washington.
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Oh, I see.
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I think.
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Before learning about the Sun, they talked with the students at North Shore about the layers of the Earth's atmosphere.
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The layers of the Earth's atmosphere.
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You know, the troposphere, closest to the Earth, and the mesosphere, which is very cold and the air is very thin.
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And, of course, the thermosphere and ionosphere, where most of the auroras occur.
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Jacob, I'm impressed.
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I've been doing more than surfing the Web and reading reports.
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Every once in a while, you have to go old school and use books.
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Well, I'm glad you haven't forgotten such a great resource.
00:10:47
But we still need to learn more about the Sun.
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Well, we're in luck.
00:10:52
Catherine and RJ are meeting with Dr. Nikki Fox to learn more about the Sun.
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She's at the Johns Hopkins Applied Physics Laboratory and works with scientists at NASA Goddard Space Flight Center.
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I'm sure they'll find the Sun very illuminating.
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Very funny.
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But I can't wait to read their report.
00:11:08
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- Idioma/s:
- Niveles educativos:
- ▼ Mostrar / ocultar niveles
- Nivel Intermedio
- Autor/es:
- NASA LaRC Office of Education
- Subido por:
- EducaMadrid
- Licencia:
- Reconocimiento - No comercial - Sin obra derivada
- Visualizaciones:
- 725
- Fecha:
- 28 de mayo de 2007 - 15:34
- Visibilidad:
- Público
- Enlace Relacionado:
- NASAs center for distance learning
- Duración:
- 11′ 10″
- Relación de aspecto:
- 4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
- Resolución:
- 480x360 píxeles
- Tamaño:
- 66.99 MBytes