Tag Archives: Magnetism

A Supernova For Breakfast (Almost)

Iron makes up less than one one-hundredth of one percent of the human body. Most adults contain just a few grams of this micronutrient. Despite its small presence in humans, it’s essential to our lives. Without it, oxygen can’t get from the lungs to the rest of the body. Iron also plays a key role in energy production and DNA synthesis.

The human body can’t produce all the materials it needs to function, so we get vitamins and minerals from food and supplements. We don’t often directly observe substances like iron, calcium, or vitamin A in our food because they’re present in such tiny amounts. Iron, however, has an unusual property. It’s magnetic, so it’s relatively easy to sort out from other ingredients!

IronCerealGif

Trace amounts of magnetic material in a whole food item aren’t strong enough to break free from the larger structure, even in the presence of a strong magnetic field, so it helps to start with something that can be broken down into small parts. Breakfast cereal is one food that’s commonly fortified with iron and is also easy to crush into a powder. Bring a powerful magnet near the powdered cereal, and iron-rich fragments jump out.

Supernova remnant 1E0102.2-7219

Supernova remnant 1E0102.2-7219, visible near nebula M76 in the Southern Hemisphere, is an approximately 1,000-year-old leftover from the explosion of a huge star. Credit: NASA/JPL/Spitzer Space Telescope

Iron plays an important part in the lives of stars, too, as the end product of stellar fusion. After lighter elements in a very massive star’s core have fused into iron, the core begins to cool and condense. Central cooling causes outer layers of plasma to fall violently inwards, collide with the iron core, and blast back out into space. This incredibly energetic explosion is where all elements heavier than iron come from, including calcium, which is also essential to human biological function. (Lighter elements, including oxygen, come from fusion inside smaller stars.) From hydrogen to carbon to iron and beyond, you are literally made of star-stuff!

Written By: Caela Barry

What is an Electromagnet?

Here at AstroCamp, one of our most popular classes is Electricity and Magnetism. At first glance, it might not be obvious how these things are related, but they are actually tied together through important physical principles.

To give you some evidence, let me introduce the electromagnet.

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This is really just a metal rod wrapped with a bunch of wire. Without any electricity going through the wire, it doesn’t do anything special. Now, let’s press the button and let electricity flow through the coil!

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What is going on? Well, to explain that we have to back up a bit. Let’s start by answering this question: What is electricity? It is the thing that runs our light bulbs, smart phones, computers, and air conditioning but what is it on a more fundamental level? What is happening?

asset-v1-pkuhighschoolph1019999_t1typeassetblockatom-light-640x360As you probably know, everything you have ever touched is made out of atoms, and these atoms have three parts: the positively charged proton, the negatively charged electron, and the neutral neutron. These charges determine how the particles interact; particles with identical charges push away while those with opposites attract.

Electricity, as you may have figured out by looking at the word, has to do with electrons. Electricity basically means moving electrons. However, physics has a bit of a surprise for us here. Whenever a charge is moving, it makes a magnetic field–if this word seems confusing, this is just what is produced by a magnet to push and pull on other magnets–around it in a circle. This happens every single time. You might be tempted to ask why, but I don’t have a great answer for you. This is just how nature is.

All we have done to make an electromagnet is sort of durn this trick on its head. By wrapping the wire into a coil, the circular magnetic field created every time an electron moves adds up in the middle. This kind of design is called a solenoid.

what-is-a-solenoid-and-solenoid-magnetic-field

This awesome illustration shows how the circular magnetic fields around each wire add up in a solenoid to make a strong magnetic field inside. All credit goes to Paul Nylander.

This might seem like a simple lab trick to convince you about the mysterious but very real connection between electricity and magnetism, but it turns out to be an incredibly useful and important design. Outside the obvious purpose of picking things up like the giant electromagnets at junkyards, electromagnets are used in speakers, hard drives, MRI machines, motors, generators, and many other things you might not expect!

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This is a view inside the Large Hadron Collider at CERN, the most powerful particle accelerator on the planet! This shoots tiny particles at very near the speed of light along a very precise track. While you might expect it to be the metal walls that keep the particles inside, the tiny particles would actually fly right out through the walls! So how do they keep those pesky particles in line? They steer them using incredible powerful superconducting ELECTROMAGNETS! Photo credit CERN.

Written By: Scott Alton

The Circle of Electromagnetism

Electricity is one element of physics that we encounter on a daily basis. It powers our televisions and our computers, and keeps the lights on at home. Magnets are something we think of as less common, only using them when we need to navigate using a compass or stick something to our fridge. But electricity and magnetism are really just two sides of the same idea!

We can see some examples of this relationship using the induction coil. There are two parts, so let’s tackle them one at a time. First, whenever electricity runs through a wire, it creates a magnetic field. If the wire is in a circle, the magnetic field will be the strongest through the middle. By stacking up several loops of wire to make a coil, we can create an electromagnet.

EddyCurrents2

Electromagnetism at AstroCamp. Pressing the button sends electricity through the wire solenoid which is coiled around a nail to create a magnetic field.

Not only can electricity be used to create a magnet, but magnetism can be used to create electricity. When a conductor, like a metal wire, experiences a changing magnetic field, an electric current is created. We can even use this electricity to power a lightbulb! This process is called induction, and it is the basic principle by which electricity is generated in almost all power plants.

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Strong neodymium magnets are rotated inside a coil of copper wire, producing a current. The needle moves back and forth, indicating the the current produced in this way is alternating, or AC current.

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This wind farm in Palm Springs employs this exact technology to generate electricity from the wind! Photo from best of the best tours!

If you want to learn more about these concepts or just see them in action, there is more about them here and hereCombining both of these ideas, we can see why the small metal ring hovers. Turning on electricity through the coil of wire creates a magnetic field that is felt by the metal ring. Then, through the process of induction, electricity is created in the ring, as you can see with the light bulb example below.

InductionLightbulb

 

The ring is now an electromagnet with electricity running through it! The magnetic field from the ring and from the coil are pointed in opposite directions, so they repel, causing the ring to hover in midair. By submerging the ring in liquid nitrogen, we can lower its resistance and increase the electric current. A stronger current creates a stronger electromagnet and the ring shoots up to the ceiling!

What is a Superconductor?

Lots of materials are conductors, meaning electricity can flow through them. However, even power lines, which have the sole job of transporting electricity, aren’t perfect. A little bit of the energy gets lost as the electricity flows. This loss of energy is called resistance. Resistance isn’t a bad thing. We use it for a lot of things. Conservation of energy tells us that energy can’t just disappear, so as the electricity dwindles it is transferred to heat. We use this to our advantage in a process called resistive heating, and it is the reason the incandescent light bulbs and electric stoves work.

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However, some unusual materials have a strange property: they have zero resistance. They conduct electricity perfectly. We call these materials superconductors. So far, the only superconductors we have found require very cold temperatures. This isn’t particularly surprising as all conductors become more efficient at low temperatures. How cold though? To give some perspective, the one in the video is known as a high temperature superconductor, and it only starts working at -300 ℉! Fortunately, liquid nitrogen is about -320℉, so they work together nicely. Scientists would really like to develop room temperature superconductors, but have had no luck thus far.

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Our superconductor is an unassuming small black disk. Most superconductors are some sort of metal oxide. Ours, Yttrium Barium Copper Oxide, is known as YBCO.

One strange property of superconductors is that they essentially reflect all magnetic fields. This is essentially because whenever electricity flows, it creates a magnetic field, and whenever there is a moving magnetic field, it causes electrons to move. For more about how electricity and magnetism interact, check here. By approaching a superconductor with a magnet, this causes the magnetic field to be bounced back by effectively creating an electromagnet, causing the magnet to float in the magnetic bed of the superconductor.

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This process is actually even cooler than the video shows. It turns out the the magnet is not only floating, it is completely held in place above the superconductor. If the magnet is lifted, the superconductor is lifted too, and even if the superconductor is inverted, the magnet is held in its own magnetic pocket. This is unlike normal magnetic repulsion, where the magnets opposite poles only push apart. This is called quantum locking. It also allows for the very cool superconducting racetrack shown below!

quantum locking

This superconductor is on a magnetic track displaying quantum locking. The low temperature of the superconductor results in a very cool cloud effect. Credit: TED

Electricity & Magnetism Belong Together

Electricity is one element of physics that we encounter on a daily basis. It powers our televisions and our computers and keeps the lights on at home. Magnets are something we think of as less common, only using them when we need to navigate using a compass or stick something to our fridge. But electricity and magnetism are really just two pieces of the same thing! Let’s shed some light on this idea.

light on

We can see some examples of this relationship using the induction coil. There are really two parts, so lets tackle them one at a time. First, whenever electricity runs through a wire, it creates a magnetic field. If the wire is in a circle, the magnetic field will be the strongest through the middle. By stacking up several loops of wire to make a coil, then we can create an electromagnet.

Picture_of_solenoid

Diagram of an electromagnet. Credit P. Wormer.

electromagnet

Electromagnet at AstroCamp. Pressing the button sends electricity through the wire solenoid which is coiled around a nail to create a magnetic field.

Not only can electricity be used to create a magnet, but magnetism can be used to create electricity. When a conductor, like a metal wire, feels a changing magnetic field, an electric current is created. We can even use this electricity to power a lightbulb! This process is called induction, and it is the basic principle by which electricity is generated in almost all power plants.

loop maybe

Strong neodymium magnets are rotated inside a coil of copper wire, producing a current. The needle moves back and forth, indicating the the current produced in this way is alternating, or AC current.

Combining both of these ideas, we can now see why the small metal ring hovers. Turning on electricity through the coil of wire creates a magnetic field that is felt by the metal ring. Then, through the process of induction, electricity is created in the ring. The ring is now an electromagnet with electricity running through it! The magnetic field from the ring and from the coil are pointed in opposite directions, so they repel, causing the ring to hover in midair. By submerging the ring in liquid nitrogen, we can lower its resistance and increase the electric current. A stronger current creates a stronger electromagnet and the ring shoots up to the ceiling!

JUMP

WELCOME TO OUR ASTROCAMP BLOG

We would like to thank you for visiting our blog. AstroCamp is a hands-on physical science program with an emphasis on astronomy and space exploration. Our classes and activities are designed to inspire students toward future success in their academic and personal pursuits. This blog is intended to provide you with up-to-date news and information about our camp programs, as well as current science and astronomical happenings. This blog has been created by our staff who have at least a Bachelors Degree in Physics or Astronomy, however it is not uncommon for them to have a Masters Degree or PhD. We encourage you to also follow us on Facebook, Instagram, Google+, Twitter, and Vine to see even more of our interesting science, space and astronomy information. Feel free to leave comments, questions, or share our blog with others. Please visit www.astrocampschool.org for additional information. Happy Reading!

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