Franklin Bell & Leyden Jar

Franklin bells are an early demonstration of electric charge designed to work with a *Leyden jar. They were invented by Benjamin Franklin in the 18th century during his experimentation with electricity. Franklin bells are only a qualitative indicator of electric charge and were used for simple demonstrations rather than research.

The bells consist of a metal stand with a crossbar, from which hang three bells. The outer two bells hang from conductive metal chains, while the central bell hangs from a nonconductive thread. In the spaces between these bells hang two metal clappers, small pendulums, which hang from nonconductive threads. A short metal chain hangs from the central bell.

The central bell's chain is put in contact with the inner surface of a * Leyden jar, while the outside surface of the jar is put in contact with the metal stand. The central bell takes its charge from the inner surface of the jar, while the outer surface charges the two bells on the conductive chains; this causes the bells to have a potential difference equal to that between the inner and outer surfaces of the jar. The hanging metal clappers will be attracted to one bell, will touch it, pick up its charge, and be repelled; they will then swing across to the other bell, and do the same there. Each time the clappers touch a bell, charge is transferred between the inner and outer surfaces of the *Leyden jar. When the jar is completely discharged, the bells will stop ringing.

Electric Fly Swatter + Coke Can = Franklin's Bell 

http://www.youtube.com/watch?v=jIL0ze6_GIY&feature=related 


What is a Leyden Jar?

A Leyden jar, or Leiden jar, is a device that "stores" static electricity between two electrodes on the inside and outside of a glass jar. It was the original form of the capacitor.

It was invented independently by German cleric Ewald Georg von Kleist on 11 October 1745 and by Dutch scientist Pieter van Musschenbroek of Leiden (Leyden) in 1745–1746.^[1] The invention was named for this city.

The Leyden jar was used to conduct many early experiments in electricity, and its discovery was of fundamental importance in the study of electricity. Previously, researchers had to resort to insulated conductors of large dimensions to store a charge. The Leyden jar provided a much more compact alternative.

Chemistry Jokes and Riddles

Q: Anyone know any jokes about sodium?
A: Na

Making bad chemistry jokes because all the good ones Argon 

Q: What is the most important rule in chemistry?
A: Never lick the spoon! 

 

Helium walks into a bar,
The bar tender says "We don't serve noble gasses in here."
Helium doesn't react. 

Silver walks up to Gold in a bar and says, "AU, get outta here!" 

Two chemists go into a restaurant.
The first one says "I think I'll have an H2O."
The second one says "I think I'll have an H2O too" -- and he died. 

Q: What did the scientist say when he found 2 isotopes of helium?
A: HeHe 

Q: Why was the mole of oxygen molecules excited when he walked out of the singles bar?
A: He got Avogadro's number! 

A proton and a neutron are walking down the street.
The proton says, "Wait, I dropped an electron help me look for it."
The neutron says "Are you sure?" The proton replies "I'm positive." 

Money has recently been discovered to be a not-yet-identified super heavy element.
The proposed name is: Un-obtainium. 

As an ion chromatography chemist I made this one up:
Anions aren't negative, they're just misunderstood. 

The optimist sees the glass half full.
The pessimist sees the glass half empty.
The chemist see the glass completely full, half in the liquid state and half in the vapor state.

 

Q: What do chemists call a benzene ring with iron atoms replacing the carbon atoms?
A: A ferrous wheel.

 

Q: If H₂O is the formula for water, what is the formula for ice?
A: H₂O cubed.

 

Q: What did the bartender say when oxygen, hydrogen, sulfur, sodium, and phosphorous walked into his bar?
A: OH SNaP!

A neutron walks into a bar. He asks the bartender, "How much for a beer?" The bartender offers him a warm smile and says, "For you, no charge".

 

Q: What do you do with a dead chemist?
A: Barium

 

Q: What did one ion say to the other?
A: I've got my ion you.

 

Q: Why did the chemist sole and heel his shoes with silicone rubber?
A: To reduce his carbon footprint.

 

Q: What do you call a tooth in a glass of water?
A: One molar solution.

A small piece of sodium that lived in a test tube fell in love with a Bunsen burner. "Oh Bunsen, my flame," the sodium pined. "I melt whenever I see you," The Bunsen burner replied, "It's just a phase you're going through."

 

Q: What do you call a clown who's in jail?
A: A silicon.

 

Q: Why do chemists enjoy working with ammonia?
A: Because it's pretty basic stuff.

 

Q: What emotional disorder does a gas chomatograph suffer from?
A: Separation anxiety.

 

Q: Why does hamburger yield lower energy than steak?
A: Because it's in the ground state.

Florence Flask was getting ready for the opera. All of a sudden, she screamed: "Erlenmeyer, my joules! Somebody has stolen my joules!" The husband replied, "Calm down, honey. We'll find a solution."

 

Q: If H₂0 is water, what is H₂0₄?
A: Drinking, bathing, washing, swimming, etc.

Titanium is a most amorous metal. When it gets hot, it'll combine with anything.

 

Q: What did one titration say to the other?
A: "Let's meet at the endpoint."

 

Q: What did the Mass Spectrometer say to the Gas Chromatograph?
A: Breaking up is hard to do.

Old chemists never die, they just stop reacting.

 

Q: What is "HIJKLMNO"?
A: H2O.

 

Q: When one physicist asks another, "What's new?" what's the typical response?
A:C over lambda.

 

Q: How did the chemist survive the famine?
A: By subsisting on titrations.

 

Q: What happens when spectroscopists are idle?
A: They turn from notating nuclear spins to notating unclear puns.

If you're not part of the solution, you're part of the precipitate.

 

Q: Why can't lawyers do NMR?
A: Bar magnets have poor homogeneity.

 

Q: What element is derived from a Norse god?
A: Thorium.

 

Q: What happened to the man who was stopped for having sodium chloride and a nine-volt in his car?
A: He was booked for a salt and battery.

 

Q: What element is a girl's future best friend?
A: Carbon.

Little Willie was a chemist. Little Willie is no more. What he thought was H₂O was H₂SO₄.

 

Q: What is the name of 007's Eskimo cousin?
A: Polar Bond.

Composite Materials Lesson (level 9-12)

http://www.teachersdomain.org/resource/npe11.sci.engin.design.composites/

In this video segment adapted from NASA 360, learn about composite materials and how they are being used in spacecraft design at NASA. Composites are known primarily for the enhanced strength and stiffness they give to objects, such as airplane wings, while being lighter than conventional materials. Objects made from composites can also hold their shape better and not experience fatigue under heat or pressure. In the video, a NASA engineer explains how and why composites are being used in place of metals in a prototype crew module design.

Background Essay

While many products we use in our lives are made of a single material like solid wood, cotton, or aluminum, more and more are made of composites. A composite is a combination of different materials, called constituents. Composites offer certain performance advantages because the constituents work together to give the resulting object special properties. Most composites are made from two or more constituent materials: a binder, or matrix, which surrounds a reinforcement. Not all composites are the product of modern advanced technology. One common example is concrete. In concrete, cement (the binder) is combined with gravel (the reinforcement).

In deciding to use one material or composite over another, engineers consider many factors, among them strength, weight, corrosion resistance, and cost. Depending on the application, other factors may also matter. In developing the next-generation space capsule, NASA engineers need materials that are strong and lightweight (or technically, less massive) but also highly shapeable and resistant to extreme temperatures and fatigue. Before settling on a solution, these engineers will have conducted multiple tests to ensure that the composite fulfills all of these needs.

While spacecraft are still largely made of metal, NASA has begun investigating alternative materials that fulfill its safety objectives but offer performance advantages. The next-generation Space Shuttle Program for manned space exploration includes a newly designed mission crew module—the part of the spacecraft the astronauts will occupy. The design being evaluated, called a composite crew module, or CCM, is made of a carbon-graphite epoxy resin composite. This means that layers of carbon fiber—a material that is just as strong or stronger than steel, at about one-fifth the mass—with graphite reinforcement will cover an aluminum honeycomb shape. The “sandwich” structure will be coated in epoxy resin and cured, or hardened, in a kind of pressure oven called an autoclave. The resulting module will possess considerable strength and be much lighter than if it were made entirely of aluminum. It will be shaped to fit into the International Space Station when docking in space, and its heat shield, located at the bottom of the module, will also be able to withstand reentry temperatures of 3000°F (1650°C).

Composite materials feature in designs beyond spacecraft. Among the many industries already using them is the auto industry. As you might expect in an era of rising fuel prices, car companies are looking for ways to combine strength with weight reduction to improve fuel efficiency. As a result, many have begun developing designs that feature a carbon-fiber body in place of the usual steel and fiberglass. Because of its high ratio of strength to weight, carbon fiber is also used in a variety of consumer products besides cars, including tennis rackets, golf clubs, fishing rods, and bicycles.

Discussion Questions

Before the Video

• What substances can you think of that are made of two or more things with very different individual properties than the combination they form?

After the Video

• What is a composite material?
• Give an example of a composite material and explain its possible advantages and disadvantages.
• How do you think you could create a composite material yourself?
• The auto industry has begun to use a carbon fiber composite in place of fiberglass. Knowing what you do about carbon fiber, why do you think it’s doing this?

Texas

Subchapter B. Middle School

§112.22 Knowledge and skills

(6.7) Science concepts. The student knows that substances have physical and chemical properties.

(A) Demonstrate that new substances can be made when two or more substances are chemically combined and compare the properties of the new substances to the original substances

§112.24 Knowledge and skills

(8.5) Scientific processes. The student knows that relationships exist between science and technology.

(B) Design and test a model to solve the problem

Topology: Quarters, Dimes, Index Card, Scissors and You

Starting Small: A Quarter Through a Dime-Sized Hole

1. Fold an index card in half, widthwise.
2. Unfold the card and trace a dime so that it is centered on the card. Use the crease as a guideline.
3. Refold the card and cut out the shape of the traced dime.
4. Now that you have a dime-sized hole, try to fit a quarter through it. It's just not possible, right?
5. Here's the trick . . . .  With the card folded along the crease, place the quarter inside of the folded card. Make sure that the quarter is centered on the dime-sized hole you already cut.
6. Grip each of the corners on the folded end of the card with your thumb and index finger. Pull the corners up and watch as the quarter slides out the dime-sized hole.

Going Big: Fitting Through an Index Card

1. Fold an index card in half, lengthwise this time.
2. Unfold the card and cut an incision along the crease that you've created. Don't cut all the way to the either end of the card. Leave 1/8" to 1/4" on each end.
3. Fold the card in half again along the same crease as before.
4. Carefully make a cut at the point your first incision stopped at a 90º angle down towards the open or unfolded side of the card. Again, remember to leave a 1/8" to 1/4" gap.
5. Repeat the previous step, this time starting from the open side of the card, leaving a gap before you get to the other incision.
6. Continue making alternating cuts along the length of the card until you reach the other side.
7. Gently pull the card open by pulling on the two ends of your original crease. The resulting, zig-zagging loop will be big enough to fit over your entire body!

How does it work?

Both of these Index Card Tricks are based on topology. Topology is concerned with continuous deformation of objects and how the way a surface or object is analyzed and manipulated determines how we understand it. Sounds complicated, right? The science of topology shows how you can alter the shape of an object without altering its size.

In the Quarter Through a Dime-Sized Hole experiment, you are able to change the perceived size of the hole without actually altering it. The squeezing and bunching of different areas of the card allow the hole to gain size along the width of the quarter.

In the Fitting Through an Index Card experiment, when you cut the card as the instructions direct you to, you do not remove any part of the card. You simply change the perceived layout in the zig-zagging loop that allows you to fit through it. In both experiments, topology allows you to change the shape or layout, but not the actual size.

SOURCE: Steve Spangler Science

A Recorded Online Physics Class

PHYSICS CLASS

https://sas.elluminate.com/site/external/jwsdetect/playback.jnlp?psid=2011-02-16.0945.M.A5BB78333AC4FEC568A60D2CE9B0FA.vcr&sid=voffice

Chlorophyll, Chromatography, Colors

Of all the natural processes around us, the annual changing of leaves from green to different shades of yellow, orange, and red is perhaps the most beautiful. But behind this show of color, there are important scientific processes at work.

Want a peek into the science behind a tree's changing leaves? With this hands-on activity, you'll see how those colors stay hidden in the leaf all year long!

What You Need:

• Leaves
• small jar (a baby food or small salsa jars work well)
• cover for jars or aluminum foil or plastic wrap
• rubbing alcohol
• paper coffee filter
• shallow pan
• hot tap water
• plastic knife or spoon

What You Do:
 

1) Have your child collect 2-3 large leaves from the same tree type. You and your child should tear or chop the leaves into very small pieces and put them into small jars.  

2) Add enough rubbing alcohol to the jar to cover the leaves. Using a plastic knife or spoon, carefully chop and grind the leaves in the alcohol. 

SAFETY NOTE: rubbing alcohol can be harmful if mishandled or misused. Use in a well-ventilated area, and avoid contact with skin.

 

3) Have your child cover the jar very loosely with a lid, plastic wrap or aluminum foil. Place the jar carefully into a shallow tray containing 1 inch of hot tap water.

 

4) Keep the jar in the water for at least a half-hour, longer if needed, until the alcohol has become colored (the darker the better). 

Twirl the jar gently about every five minutes. Replace the hot water if it cools off.

5) Have your child cut a long thin strip of coffee filter paper. 

Remove the jar from the water and uncover it. Place a strip of filter paper into the jar so that one end is in the alcohol. Bend the other end over the top of the jar and secure it with tape.

The alcohol will travel up the paper, bringing the colors with it. 

 

6) After 30-90 minutes the colors will travel different distances up the paper as the alcohol evaporates. You should be able to see different shades of green, and possibly some yellow, orange or red, depending on the type of leaf.

What happened?

Chlorophyll is a green compound that hides the other colored pigments present in leaves. In the autumn chlorophyll breaks down, allowing the other pigments to be seen. The mix of pigments in a leaf may be separated into bands of color by the technique of paper chromatography.

Chromatography involves the separation of mixtures into individual components, which you just did using alcohol and energy (heat). Then, by "absorption" and "capillarity," separation can take place!
The paper holds the substances using absorption, while capillarity pulls the substances up the paper at different rates. Pigments are separated on the paper and show up as colored streaks or bands.
Pretty cool, huh?

As possible extension activities compare different types of leaves and/or experiment with other types of paper.

By Mike Calhoun and Michael Calhoun

Mike is a 20-year veteran science teacher, and runs an online business (www.scienceinabag.com). Over the years Mike has studied trends in science, education, and finance, conducting research, developing programs, and writing articles on these topics.

SOURCE: Education.com

LAGNIAPPE:  Chlorophyll in Olive Oil

Mysterious Appearing Colors (Benham's Disk)

Video followed by explanation. Source link.

We know that red and blue make purple, blue and yellow make green, and that yellow and red make orange. Most of all, we know that when you mix black and white you get…um…a rainbow. You can use black and white to make actual colors. See just how the spinning illusion can trick your eyes. Materials Printer White paper Craft paper or card stock paper Glue stick Toothpicks Downloadable template Click on the downloadable template and print it out on craft paper or card stock. Cut out one of the four circular designs. Break a toothpick in half and stick one of the halves through the design you cut out. Make sure the pointed end of your toothpick is on the blank side of the disk. You've made a top. Give the top a spin and watch the design on the top. What do you see? Repeat steps 2-4 with the other three circular designs. What do you notice about these designs as they spin? Observations Once you've got the disk spinning, take a look at the circular design on it. What's going on over there? Where did all of those colors come from? *Note* Some of the disks only produce colors at certain speeds, some faster or slower than others. How does it work? Hmmm… how does it work? That's a really good question. We honestly don't know for sure. No one does. But we've got some pretty good guesses. The black and white circular design that you printed out and pasted to your cardboard is called Benham's Disk.  Benham's Disk originated over 100 years ago and, when spun at the right speed, creates a changing pattern of light that is noticeable by your retina.  Many scientists think that the visible pattern of light created by the disk resembles a "code" similar to what the brain receives when the eyes see color. The rapidly spinning black and white disk tricks the brain into seeing the colors. Crazy!