Tag Archives: Experiment

Homopolar Motorcar

A homopolar motor is a device that relies on flowing electricity, magnetic fields, and the interaction between the two. It consists of a voltage source, neodymium magnets, and a conductor that allows electricity to flow. And it’s super easy to make yourself!

What you’ll need:

  • 1 AA battery
  • 2 neodymium magnets
  • Thick copper wire

 

————

Step 1

Place one of your magnets onto the positive terminal of the battery.

Holompolar Motorcar Step 1

Step 2

Use the already attached magnet to test the poles of the second magnet. Figure out which sides are repelling each other, and place the second magnet so that the repelling side faces away from the battery. This way, either both South poles or both North poles are facing outwards! (Note: it doesn’t matter which, as long as they’re consistent with each other!)

Holompolar Motorcar Step 2

Step 3

Shape your copper wire so that it can hook easily on the inside of the magnets. Try to maximize the amount of contact it has with the magnets on BOTH sides, so as much electricity as possible can flow. When it’s been properly shaped, hook the wire onto the motor!

Holompolar Motorcar Step 3

Instead of using a wire, you could use a sheet of aluminum foil! Lay it as flat as you can on a level surface, away from any metals that might attract your magnets. Make sure there are no tears or holes in the aluminum. Then place your battery-magnet motor on top! The aluminum will allow electricity to flow!

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When a magnetic field is applied to an object carrying electricity, it applies a force to that object. This is called the Lorentz Force. Due to the electricity flowing through the magnets, this force becomes a torque, causing the motor to rotate and drive forward!

Homopolar Motorcar Rollin

Written By: Scott Yarbrough

For Mimi by Twin Musicom is licensed under a Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/)

Artist: http://www.twinmusicom.org/

What is Jacob’s Ladder?

If you’ve taken our Electricity and Magnetism class, you’ve seen this device before! You press a button and an electric arc rises to the top of two tall wires. This is the Jacob’s Ladder! But what’s happening here? 

Jacob's Ladder

The base of the Ladder is a transformer — a device that changes an incoming voltage. In the Ladder’s case, it increases it by a huge amount. That voltage is put into one of the vertical wires, increasing its electric potential. The electricity needs to flow somewhere, so it ionizes the air to jump to the other vertical wire. As the electricity arcs, it heats up the ionized air, which causes it to rise. As the wire get further apart, it becomes more and more difficult for the electricity to reach, and the arc eventually stops. Then the transformer builds up the electric potential again, repeating the process all over again. Though as electricity flows through the wires, they heat up. The hotter they are, the slower the electricity flows. Eventually, you’ll notice the arc having trouble getting to the top as it travels slower and slower.

Jacob's Ladder 2

This is just one of the many cool electricity demos we have at AstroCamp! Be sure to check out this and all the others on your trip.

Written By: Scott Yarbrough

 

What is Ferrofluid?

Back in the early 1960s, a fledgling NASA was presented with lots of new problems. Going to space was unlike anything humans had ever done, and engineers and scientists were constantly searching for answers to issues they had never even considered before.

ferrofluid 2 2One of these problems was dealing with the properties of a liquid in low-gravity environments. On Earth, a liquid will stay at the bottom of its containers as gravity pulls it down. But without gravity, the liquid will float all around its container, forming spheres of liquid.

Since the rockets used by NASA relied on liquid fuel, there was a problem getting the fuel pumped to the engines once the spacecraft was in orbit. Several ideas were tried, and though NASA eventually settled on small solid rockets to settle the liquid fuel near the intake, one of the ideas proposed by a scientist named Steve Papell was a ferrofluid fuel.

A ferrofluid is any liquid with metallic metal suspended in it. The metal has a special material coating to prevent the small pieces from attracting or repelling each other, but when the solution is exposed to an exterior magnetic field, the ferrofluid is attracted to the magnet. It also increases in density and becomes somewhat rigid.

ferrofluid 2 1

When Steve Papell suggested using a magnetic fuel, his idea would be to control the flow of the fuel by using magnets. Instead of letting the

liquid blob in the center of the tank, it could now be held towards the fuel intake and make the system more efficient. Though it was a good idea, NASA found other, better solutions for the rocket issue.

That didn’t mean the end of ferrofluids, however. Another scientist named R.E.Rosensweig improved upon the design and developed a new branch of fluid dynamics known as ferrohydrodynamics.

Since then, ferrofluids have been used in many devices — the most common of which is in electronic devices such as hard disks, using it to form liquid seal that will be held in place by magnets. This seal prevents dust and other materials from entering the hard drive.

Despite its practical uses, ferrofluid is just cool to look at. If you ever have the chance, grab a magnet and play around with it!

Written By: Scott Yarbrough

Pendulums and Gravity

In the video above, I talk about how pendulums actually work. If you haven’t watched it, the principle is simple: an object is suspended from a fixed point and allowed to swing back and forth – the mass of the object and the time it takes to swing back and forth are independent of each other, relying only on the length of the string and the strength of gravity.

Normally, you’d think of gravity on Earth’s surface as being constant, but the Earth isn’t a perfect sphere, meaning that the force of gravity near the equator is slightly weaker than at higher or lower latitudes. And how did we discover this fact? Pendulums!

Pendulum and Gravity 1

In the year 1671, a French scientist named Jean Richer travelled to French Guiana. Among several experiments and astronomical observations during his two-year trip was to take measurements with a clock pendulum.

He set up the pendulum in the same way I did in my video, but he adjusted the length of the pendulum so that one half-swing took exactly one second, a common technique at the time. What he found was that the pendulum length needed to be slightly shorter than it did back in Paris, by about 3 millimeters. Though a small difference, it was significant enough to begin a discussion about the varying gravitational field of Earth.

Pendulum and Gravity 2

This was later proved by Isaac Newton by determining that due to the Earth’s rotation, it was thicker at the equator, meaning the surface was further away from Earth’s center of mass. This was further supported by Newton’s idea that gravitational force decreases as the distance between two objects increases.

Scientists started to use pendulums to take measurements of the gravitational field in other locations and began to create a model of the Earth’s true oblong shape. Since then, we’ve developed more accurate methods to measure the same thing, but they were pioneered by those first efforts.

Written By: Scott Yarbrough

Video Music: Funky Chunk Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 3.0 License

http://creativecommons.org/licenses/by/3.0/

Bubble Hurricanes

CAUTION: This experiment uses a hot plate. Please use adult supervision if attempting to recreate.

Bubbles are a great resource for fun and physics. They provide interesting insight for optimization and can even be used as models for atmospheres. Scientists are able to use bubbles as models for the atmosphere because they are very thin compared to the sphere they enclose, just like Earth and it’s atmosphere!

hurricanes

To show this, you can do a very simple experiment, but be sure to have supervision since there is a risk of burn. All you’ll need is a stove top, a metal dish, soap, and a straw. Heat up the metal dish, pour a soap solution on top and blow a bubble into it, using the straw so as to not burn yourself.

hurricanes 1

You will be able to see vortices form in the film of the bubble. These vortices mimic those of how hurricanes and cyclones form. As the soap film is heated up from the bottom the vortices are formed. The strength of the vortices intensify then die in a uniform way. This is due to convection currents.

Convection currents are the transfer of heat by the mass movement of heated particles into an area of cooler ones. Convection currents on Earth is what causes things like weather and storm patterns. The hotter the planet gets, from geothermal heating and climate change, the more intense weather we will experience.

The same phenomenon can be clearly seen in our bubble hurricanes. The hotter the soap solution becomes, the more intense the vortices will be, but they also die out much more rapidly.

Credit: University of Bordeaux in France

Written By: Mimi Garai

Can you Freeze Antifreeze?

CAUTION: Antifreeze is a very powerful chemical that, if ingested, can cause serious illness or death. Do not attempt to use it without adult supervision. All appropriate safety precautions have been taken for the filming of this video.

If you are from a colder part of the world, then you know how important antifreeze is. It is mainly used for pipes in homes and cars. But it no longer becomes useful if it itself freezes. Can that happen?

antifreeze

Antifreeze is a substance that lowers the freezing point of water, protecting a system from the ill effects of ice formation. The purpose of antifreeze is to prevent a rigid enclosure from bursting due to expansion when water freezes. Water usually freezes at about 0˚C or 32˚F, but when antifreeze is added to it that changes to being able to freeze at about -50˚F.

Knowing this, we wanted to see the affects if we poured some into liquid nitrogen and pour liquid nitrogen into antifreeze.

anitfreeze 1

It turns out that it freezes, but in a weird way. It actually takes a long time for the antifreeze to freeze. The -321˚F liquid nitrogen does the trick, but will take more than a minute to freeze it all the way through, compared to water which takes a few seconds. The solid antifreeze is not uniform, and does not look like the liquid. It is opaque compared to the clearish liquid, and almost cloud like in shape!

Written By: Mimi Garai

How to Supercool Water

Water is usually pretty predictable. At standard pressures it will boil at 100˚C and freeze at 0˚C. However, under special circumstances it might surprise you. Dihydrogen monoxide can become supercooled, dropping below 0˚C while maintaining the liquid phase of matter.

water

Here’s how:

  • Acquire distilled or purified water.
  • Fill an empty bottle with tap water (this is your control).
  • Place all three bottles in the freezer at the same time
  • Leave them in for roughly 2 hours (if all of the water was originally at room temperature)
  • The timing of this will vary with each freezer. After the first hour, check on the bottles periodically to check for signs of freezing.
  • The bottle filled will freeze before the purified water. At this point you will know that the purified water is below zero, and is ready to be removed from the freezer.
  • Take it out, give it a hard slam on the table, and watch the H2O turn from liquid to a solid right in front of your eyes!

Water cool

The liquid will flash freeze into a solid. By hitting it on the table, the water molecules are bumped into alignment in a more crystalline structure, typical in solid ice. This induces a chain reaction that you can follow all the way down the bottle!

Written By: Mimi Garai

The Coolest Molecules

CAUTION: This experiment uses dry ice (-109˚F) and liquid nitrogen (-321˚F). Proper safety equipment should always be used when handling these substances.

Physics tells us that pressure, volume and temperature are all linked when talking about gases. So what does this have to do with solid carbon dioxide (dry ice) and liquid nitrogen? When dry ice is placed into a balloon at room temperature, which is then tied off, it will start to warm up.

molecules

Since the ambient air temperature is roughly 65˚F, the air that surrounds the balloon is more than 150 degrees warmer than the dry ice! This hug difference adds energy to the dry ice turning it into gaseous carbon dioxide through the process of sublimation. Sublimation is the phase transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase.

molecules cool

Now that there is a balloon full of carbon dioxide gas we can cool it down with something colder than dry ice. This is where liquid nitrogen comes in. The balloon gets dunked into a bowl full of the -321˚F liquid! Cooling the gas in the balloon down means that it loses energy making the molecules start to clump, making the balloon lose volume. It will turn the carbon dioxide gas back into a solid through the process of deposition. Deposition is basically the opposite of sublimation, turning the gas directly into a solid.

molecules done

This process of cooling and warming to change the balloon’s volume can be repeated over and over again. Or, with the inflated balloon, dunk it in the bowl of liquid nitrogen, take it out, and before it can expand again, rip it open to see the solid carbon dioxide for yourself!

Written By: Mimi Garai

 

Pendulum Waves

You’ve already seen the way a no-flinch pendulum works, so now we are changing it up. This contraption is host to many pendulums next to each other but not touching. When you raise them up and let them go all at once, you can see something truly mesmerizing.

pendulum wave

They will all start to fall at the same rate, thanks to the laws of gravity, but after the first swing the will not be synchronized. This is due to them being uncoupled, or not connected, and to the length of each individual pendulum. The pendulum furthest away has the shortest length and the closest pendulum has the longest. All of the pendulums in the middle gradually become longer as they get closer.

The period of a pendulum is mostly dependent on its length. Since the lengths gradually increase, so will the periods, causing them to become out of sync. However, that can cause some pretty visually pleasing effects!

pendulum wave middle

Of course, given enough time, all of our pendulums will eventually line back up again in the end. But not before going through some other awesome patterns, as well as what may look like chaos.

pendulum wave end

This is not the easiest DIY project, but it is possible to recreate, so give it a try. Or you can always find it online or in store, but either way it is definitely worth seeing in person. Let us know what you think!

Written By: Mimi Garai

Exploring Water

CAUTION: DO NOT ATTEMPT THIS AT HOME

Here is an experiment that even the professionals at AstroCamp will not dare to perform. Water can become superheated in a closed system, like that in a microwave, and become extremely dangerous. Superheated water is liquid water under pressure at temperatures between the usual boiling point, 100 °C, and the critical temperature, 374 °C.

Water

Superheated water can be stable because the liquid water is in equilibrium with the vapor. However, if water becomes superheated due to this equilibrium and a lack of bubbles or impurities, then it will all of a sudden boil if there is a change in the system. This could be a simple as jostling the liquid, introducing something like a spoon, tea bag, or even a tiny piece of dust!

water 1

Smooth containers do not have bubbles of air clinging to their sides. Rough or scratched containers may hold microscopic bubbles in their cracks, becoming nuclei for boiling. These nuclei provide a source for the water to release heat and energy in a safe way. But with a smooth container, when a nuclei is added, the superheated water will explode!

Written by: Mimi Garai

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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