We've Been Building Robots...

If you've been wondering where we went, the past few months have been spent developing projects for two book projects. One is an activity book for ages 9-12 about Robotics. You can see some of them on the Facebook fan page I created. (A companion blog is forthcoming.)

The other book is a joint project with the other editors of GeekMom! I'll post more news of that as it develops.

More Integrated Science

The Ceceri family will be continuing our study of Integrated Science this year, but with one less student. John III is now off at Rochester Institute of Technology, where he is in the Interactive Games and Media program.

As a going-away present, I made him this great fish tank, using genetically-modified fluorescent GloFish. Watch the video to see what happens when you turn on a blacklight!

The mini-aquarium I put together is a project I've written about before on Home Biology. Here are the instructions, which I ran on GeekMom last week. 

Keep watching this space for more labs related to the Joy of Science video series. We'll also be trying out some electronics projects as I work on a new children's activity book about robotics. I'm looking forward to another fun year!

Foam Plate Speakers

For science this week, we decided to experiment more with audio devices. (The episode of  The Joy of Science we had just watched was about properties of matter, including magnetism, and mentioned that speakers worked because magnets changed shaped.) Since we had already built a radio, this time we built a speaker. The speaker was much easier to make and much less elaborate than the radio, and we were able to have it working in about a half-hour. Despite requiring some fine-tuning, we were able to get it to work very well.

This simple and elegant project was designed by Jose Pino. You can see it being made in this Make Magazine YouTube tutorial.

We didn't test our speaker out with our foxhole radio, because the volume is so low on both devices. Instead we used an mp3 player. But we plan to try our homemade radio with the speaker sometime in the future.


Materials:

A foam plate
Two strips of paper
Two business cards (we just cut an index card in half for this)
Tape
A hot glue gun
Magnetic copper wire (Jose Pino recommends using AWG 32)
Neodymium magnets
An audio plug
A piece of cardboard

1. We started by rolling one of the strips of paper over the magnets. We then taped the roll closed, being careful not to tape it to the magnets.

2. Next, we rolled the other strip of paper around the first strip, and taped it closed. We cut this strip a little less wide than the first. This made the outer strip stick out a bit more than the inner one.

3. Keeping the magnet inside the tubes of paper, we coiled the copper wire around it, using about 50 turns. Leave a few inches of copper wire uncoiled on each end.

4. We then pulled the magnet out of our paper, along with the inner strip (we made it wider so that it would be easier to pull out.)

5. Discarding the inner strip, we then hot-glued the outer to the bottom of the foam plate, being careful to have it in the center.

6. Next, we hot-glued the magnet to the cardboard. After that, we folded the business cards in an accordion shape, we glued them to the bottom of the plate, one on each side of the coil. We then put hot glue on the bottoms of the cards, and glued them to the cardboard base, making sure that the coil would go over the magnet.

7. We tested the wires by touching the ends to either end of a battery. This is what happened:





8. To connect our speaker to a sound system, we needed an audio plug. We got one by cutting the end off a cheap set of earbuds from the dollar store. FIrst we had to sand off the coating from each end of the copper coil wire and strip the rubber insulation from the ends of the audio plug. Because the earbuds were stereo, we needed to connect one wire from each earbud to each of the copper coil wires in order to hear both sides. (We're not sure that worked well, though.)

9. Finally, we plugged the audio wire into a music device. We found that MP3 players worked the best.



How it Works:

The speakers operate largely on the same principle as the piezoelectric earpiece we used in our radio experiment. The coil serves as an electromagnet. It receives electrical currents from the audio plug, which gives it either a stronger or weaker attraction to the magnets. This causes the foam plate to bounce up and down, creating sound vibrations.

More Plasma Fun

We had so much fun playing with our plasma ball, we decided to try making some plasma of our own! According to YouTube, this is easy to do if you have (a) a microwave and (b) a grape. This experiment was about the most exciting thing we have ever tried in our kitchen. Here's how to do it:

Materials

• large juicy grape
• knife
• microwave-safe plate
• microwave-safe tall heavy glass, preferably tapered (like a beer or coke glass)

1. Cut a grape in half across the middle. Take one half and cut the long way, leaving a bit of skin to hold the halves together.
2. Open up the halves and place grape on a small plate. Remove the rotating turntable in the microwave. Place the plate in the microwave.
3. Turn off the lights. Set the microwave for 5 seconds (but stand by to hit "Stop" when needed). You should see sparks and a puff of “flame.” That is the plasma.

Here's something even cooler: To make a kind of Jacob's Ladder, cover the grape with the glass. Make sure the glass is sturdy, or it may break! Set the microwave for 5 seconds (but stand by to hit "Stop" when needed). You should see blobs of plasma rising in the glass over and over.



Here's an explanation of how a microwave creates plasma from Naked Scientists:

A microwave oven heats up food using microwaves - these are electomagnetic waves that cause electric current to move back and forth between the two halves of the grape. This current is concentrated in the piece of skin between the two, which will heat up and dry out. The current then has to move through the air, creating a spark. 

The spark is created when the electric field rips electrons off atoms. These can then move freely and carry electric current. A gas with free electrons and positive ions is also known as a plasma. This plasma conducts electricity and can absorb microwaves. Sometimes the plasma gets big enough to absorb enough microwaves to keep growing.

And from Physics Forums:

There's two clean grape surfaces that are separated by a fraction of a millimeter near the corner of an air wedge. The electric field between the grape portions at the tip of the wedge is large enough to cause breakdown in the air gap, making a plasma ball there.

Plasma: The Fourth State of Matter

This week's episode of The Joy of Science was about States of Matter. Most people are familiar with three: solid, liquid, and gas. But there is a fourth state of matter: plasma.

Plasma is a gas-like field made up of charged atomic particles – negative electrons and positive ions (atoms which have lost some of their electrons, and so have an excess of positrons). As they move, these particles generate electricity and magnetic fields. Plasma requires low pressure and extremely high temperatures. On Earth, plasma only occurs naturally in the form of lightning, polar auroras, and extremely hot flames. However, plasma is actually the most common state of matter in the universe, since it makes up stars and other celestial bodies, as well as the space in between.

Plasma was first identified in 1879 by Sir William Crookes, who called it "radiant matter." It can be created artificially by running an alternating electric current through certain types of gas in vacuum tubes. This “knocks electrons” off the atoms inside.

In this experiment, we decided to use a plasma globe to observe some properties of plasma. A plasma globe is a type of lamp that you can buy in a novelty shop, museum gift shop, or through a science supply house. Inside the glass bulb of the plasma globe is a Tesla coil. This creates a plasma field of electrically charged particles, which look like small tendrils of lightning.

When we turned the plasma globe on and touched the glass, the tendrils of lightning concentrated at the spot that was touched. Touching it in more than one place at the same time created several points of concentration. Our plasma globe also had a setting that made it react to sound waves. We put mp3 speakers next to it and watched it flick on and off in relation to the music. Interestingly, it was more affected by frequency (how high or low the note was) than to volume. It reacted very strongly to particular notes and not at all to others. This reminded us of seeing the band ArcAttack at Maker Faire NY. ArcAttack creates music using giant Tesla coil-driven plasma arc speakers.



The first experiment we did was to hold different kinds of unplugged light bulbs near the globe. As described on the Plasma Ball experiments page on the Wonders of Science website from the University of Wisconsin, some electrons from inside the globe travel through the glass to the light bulbs.

Inside the bulbs are gas molecules. In fluourescent bulbs, molecules of mercury vapor become excited by the energy of the charged particles bombarding them from the plasma field. Electrons in the mercury atoms make a quantum jump to a higher energy level (or shell) around the atom's nucleus. When they return to their previous energy level, the extra energy is given off in the form of light. When they are plugged in, fluourescent tubes also operate by creating plasma fields out of the mercury gas.

We got good results with fluorescent and neon lights, above and in the videos below. We also tested Halogen and Xenon bulbs, but were unsuccessful.





Our second experiment was more elaborate. First, we balanced a penny on the top of the globe. Next, we took another penny, and close to the penny balanced on the dome, but not touching it. As in the first experiment, some electrons from the plasma field traveled through glass and were carried by the penny on top as an electrical current. The penny was able to carry a current because they are made out of a conductive material, copper. Holding a second penny above the first drew the electricity throught the air, creating a tiny spark. You can just barely see the spark in the photo below; in the video you can see and hear the tiny crackle as the pennies spark.

We also tried sending sparks to our fingers. We found that, if we weren’t grounded, we could send a spark from the penny to one of our fingers without feeling a shock!

Stay tuned for more exciting plasma experiments in the second part of our report on States of Matter!

Isolating DNA -- a long polymer chain

DNA, which stands for Deoxyribonucleic acid, is made up molecules known as nucleic acids. These were first identified by Swiss physician and biologist Johannes Friedrich Miescher in 1869, who called them “nuclein” because they were found in the nucleus of the cell. Every type of life form known contains nucleic acids, in the form of DNA or RNA (ribonucleic acid).

Oswald Avery received the Nobel Prize in 1943 for confirming that DNA carried genetic information. Each strand of human DNA is divided into 23 pairs of chromosones, which in turn contain hundreds or thousands of genes. Genes record information in the form of chemical codes about how to build the proteins and other molecules which make up living organisms.

DNA is one of the longest type of polymers, or chains of molecules. Strands of human DNA are 6 feet long. In 1950, scientist Rosalind Franklin used X-ray crystallography to find that DNA is made up of two long polymers, or chains of molecules, twisted into a shape called a double helix. In 1953, James Watson and Francis Crick discovered that the strands were connected by crossbars, like a ladder. They won the Nobel Prize in 1962 for uncovering DNA’s structure.


Isopropyl (rubbing) alcohol (70 or 91 percent)
Clear plastic cups
Plastic spoons
Small plate (preferably disposible)
Drinking water
Salt
Dish soap
Blue food coloring (optional)

Step 1: Chill the alcohol
Place the bottle of alcohol in the freezer to chill while preparing the next steps. (Do not leave in long enough to freeze!)


Step 2: Gather the DNA
In the plastic cup, mix ¼ teaspoon of salt in 1/4 cup of water. Swish the salt water around in your mouth for a minute, making sure it reaches the inside of your cheeks. Spit all the water back in the cup. Do not swallow! (If you prefer, you can also use Gatorade, which is sweeter.)

Cells from the inside of your cheek mix with the salt water and are carried away when you spit. Above is a photograph of cheek cells under a microscope. You can see the nucleus inside each cell.

Step 3: Release the DNA from your cheek cells
Put a drop of dish soap on the plate. Touch the spoon to the soap, and then dip it in the cup of salt water. Gently stir once or twice. Cells are contained within membranes that are made up of fats. The soap solution breaks down the fat molecules, just like soap breaks down grease on your dishes, and releases the contents of the cell.

Step 4: Add the alcohol
Remove the alcohol from the freezer. Pour about a quarter of a cup into a second plastic cup. If desired, add a drop of blue food coloring to make the alcohol easier to see. Stir until evenly mixed. Take the salt water cup and tilt to one side. Hold the cup of alcohol up so that the lip touches the tilted cup. SLOWLY pour a little alcohol down the inside of the cup so that it floats on top of the salt water without mixing. Continue until there is about an eighth of an inch of alcohol on top of the salt water.

Step 5: Watch the DNA strands appear
Wait a few minutes and you will see long strands or clumps of a sticky white substance start to come together in the alcohol layer. This is the DNA from thousands of cheek cells in the salt water. The DNA cannot dissolve in the chilled alcohol, so it precipitates out (comes out of solution as a solid).
Variation: If you want to remove the DNA to look at it through a microscope, dip a toothpick into the alcohol layer and twirl it to gather up the sticky DNA. Place on a glass microscope slide. You can also save the DNA in a small clear container with a little extra salt water. Keep tightly covered.

More information:

http://tang.skidmore.edu/pac/mtm/DNA/index.html
www.nespal.org/oziasakinslab/edout/AnimalDNAExtraction.pdf
http://www.vampirewear.com/dna.html
http://nature.ca/genome/05/051/0511/0511_m204_e.cfm
http://www.californiasciencecenter.org/Education/GroupPrograms/HomeSchool/docs/DNA.pdf

Splitting Saltwater

Last week we watched an episode of  The Joy of Science dealing with elements that have an affinity for one another, like sodium and chlorine.  In the great Theo Gray book Mad Science, he shows that combining sodium and chlorine to make your own salt results in quite a bang.I was looking for other interesting sodium-related YouTube videos when we came across one that showed a cool way to split salt into its component elements.

Above you can see our version of the experiment. What we did is explained below.

Saltwater Electrolysis

Materials:

-Salt
-One 9-volt battery
-Two spoons
-A medium-sized glass bowl

Steps:

1. Fill the bowl with warm tap water, and stir in a spoonful or so of the salt.


2. Place the two spoons in the water, being careful not to let the two spoons touch each other.

 3. Hold the ends of the two spoons to the battery connectors, one spoon on each connector.

4. Within a few seconds, you should see tiny bubbles coming off of the spoons. You will also notice what looks like smoke coming off the water.

5. After holding them in a minute or so, you should be able to see the water begin to turn murky yellow.

6. After several minutes, the water starts to turn dark green.

Here is an explanation of what's happening (from the NASA Aquarius website):

In chemistry, electrolysis is a method of separating bonded elements and compounds by passing an electric current through them. An ionic compound, in this case salt, is dissolved with an appropriate solvent, such as water, so that its ions are available in the liquid. An electrical current is applied between a pair of inert electrodes immersed in the liquid. The negatively charged electrode is called the cathode, and the positively charged one the anode. Each electrode attracts ions which are of the opposite charge. Therefore, positively charged ions (called cations) move towards the cathode, while negatively charged ions (termed anions) move toward the anode. The energy required to separate the ions, and cause them to gather at the respective electrodes, is provided by an electrical power supply. At the probes, electrons are absorbed or released by the ions, forming a collection of the desired element or compound.

One important use of electrolysis is to produce hydrogen. The reaction that occurs is 2H2O(aq) → 2H2(g) + O2(g). This has been suggested as a way of shifting society towards using hydrogen as an energy carrier for powering electric motors and internal combustion engines. Electrolysis of water can be achieved in a simple hands-on project, where electricity from a battery is passed through a cup of water (in practice a saltwater solution or other electrolyte will need to be used otherwise no result will be observed). Electrolysis of an aqueous solution of table salt (NaCl, or sodium chloride) produces aqueous sodium hydroxide and chlorine, although usually only in minute amounts. NaCl(aq) can be reliably electrolysed to produce hydrogen. Hydrogen gas will be seen to bubble up at the cathode, and chlorine gas will bubble at the anode.

According toWikipedia, this is the formula for the chemical reaction taking place:

2 NaCl + 2 H2O → Cl2 + H2 + 2 NaOH

That means, two sodium chloride molecules (which is the salt) plus two dihydrogen monoxide molecules (also known as water) becomes one chlorine molecule, one hydrogen molecule, and two molecules of sodium hydroxide (which is also known as lye). So in our experiment, the bubbles were hydrogen, the "smoke" coming off the water was chlorine gas, and the yellow color of the water was the sodium, in the form of lye.