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Suit Yourself™ International Magazine #28: Marshmallow Lightspeed

  

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Suit Yourself™ International Magazine #28:  Marshmallow Lightspeed

 

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MARSHMALLOW LIGHTSPEED 

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This is the 28th in our articles series and I hope this information is helpful!

All previous articles in the series can be found in our Library and in the Magazine Archives.  Upon request, reprint permission and an addendum of substantiating resources are available for all magazine articles. When requesting reprint permission or addenda, please include the issue date and full issue title. All magazine articles are copyright © Debra Spencer, Suit Yourself ™ International. All rights reserved. ISSN 2474-820X. 

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One of the best reasons to measure light's speed with marshmallows in a microwave oven, aside from eating the marshmallows afterwards, is the fun of learning about microwaves and the electromagnetic spectrum.  You may or may not realize that some people are afraid of microwave ovens, but they will use mobile phones and computers and try to tan in the sun! Since ignorance of the electromagnetic spectrum and its' properties is on a par with never having had a sex education, this little article attempts to have fun while hopefully helping to explain a bit of EM.  However, the most important and necessary reason to study anything is that it gives pleasure and entertainment. Without this, the study of anything isn't worth the effort, however profitable the knowledge might be.

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Islesboro Mad Science Event, photo by Marjorie Mills, 170727. 

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This is a straightforward experiment you can safely do at home using your microwave oven to determine the speed of light. Instructions are below.

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Home Reception, Electromagnetic Spectrum Diagram.

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WHAT YOU WILL NEED

A ruler.

A full power microwave oven, that has a removable turntable.

A bag of Mini-marshmallows.

A board, or thick paper towel, or microwave-safe dish (bigger is better).

The sticker on the back of your microwave will tell you the frequency in MHz at which your microwave oven operates. 
Mine says 2450 MHz.
Write down the frequency of the microwave oven, in megahertz, that is stated on the sticker on the back of the oven.
Megahertz MHz = 106 Hz

 

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Write down the frequency of the microwave oven, in megahertz, that is stated on the sticker on the back of the oven.

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THE FUNDAMENTAL PHYSICS FORMULA for this experiment:   
Velocity, Speed of a Wave (C) = Frequency (F) x WaveLength (L)

For the Speed Of Light (just choose one!):
The agreed exact value for the speed of light in vacuum: 299,792,458 metres per second (approximately 3.0 × 108 m/s,  or 186,282 mi/s, often rounded up to 300,000,000 m/s).

The actual speed of light is 3.00 x 1010 cm/s. 

The true speed of light in air is 3.0 × 108 m/s.

Reference: https://en.wikipedia.org/wiki/Speed_of_light

The speed of Light (abbreviated as C) is the speed of the wave, equal to the velocity.
Velocity is the Frequency of the wave multiplied by the waveLength of the wave.

Because the wave is a standing wave, ping-ponging back and forth inside your oven, there are two nodes for each wave. The distance between the melted sections of the marshmallows is WaveLength divided by two, because there are two nodes for each standing wave. When measuring, measure the distance from the center of one melted marshmallow to the center of the nearest melted marshmallow. 

For the Frequency, use whatever frequency is stated in hertz on the sticker on the back of the microwave oven.
Mine says 2450 MHz.  Megahertz MHz = 106 Hz

There is usually some uncertainty in the measurement so an approximation is fine; centimeters are more precise than inches. How close can you get?

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There is usually some uncertainty in the measurement; these are NOT marshmallows.

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INSTRUCTIONS

Melting time depends primarily on the frequency at which your microwave oven operates. These instructions will vary depending on how powerful your microwave oven is.
 
1. Get the miniature marshmallows ready to put in the microwave.  
Lay them out on a board, or thick paper towel, or inside a microwave-safe dish (bigger is better) so they are only one layer deep and all the marshmallow sides are touching.

 

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Correctly arrange the marshmallows so that they are one layer thick and with their sides touching.

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2. We don’t want the marshmallows to rotate once inside the microwave oven. If your microwave doesn’t have a removable turntable, it means that the turning mechanism is elsewhere and you’ll need to find a regular microwave oven to try this experiment. 

3. Open the microwave oven door, and remove the rotating platform. If there is a T- or X-shaped piece that drives the rotation, and it is removable, remove this also.  Don't worry! These both pop on and off easily and you won't harm the oven by removing them temporarily.
 

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Remove the interior rotating platform and also the support bracket if there is one.

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4. Check that the marshmallows are laid out only one layer deep, and spread out evenly across the board, thick paper towel, or dish. Place them inside the microwave oven and shut the door.

5. Run the microwave at full power for 30 seconds, or more, until you see parts of the marshmallows starting to bubble. 

Check the marshmallows, leaving them inside the oven. Wait a moment for them to cool, and check to see if you can find areas where some have heated or melted while other areas have not.
 

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Check the marshmallows; look for melted areas.

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You should be able to see these haven't melted evenly; in fact, you should see some sort of melted/unmelted pattern across the marshmallows running in some direction.

Marshmallows inflate during heating; they'll deflate again fairly quickly as they cool, but it should  be possible to tell the “hot spots” from the rest. 

 

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Marshmallows expand during heating, and contract again as they cool.

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5. Find the two closest melted marshmallows, and using your ruler, measure the distance between them. Measure the distance from the center of one melted marshmallow to the center of the nearest melted marshmallow.  The distance you're measuring is the distance between the nodes of the standing microwave, and is thus HALF the full wavelength of a microwave bouncing back and forth as a standing wave in your oven.

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Find two neighboring melted areas, and as precisely as possible, measure between them.

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6. Do the math (Velocity, Speed of a Wave (C) = Frequency (F) x WaveLength (L) ).

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Check out the speed of light!

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7. THEN Eat em up!
 

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Marshmallow and banana pancakes, photograph by Harry Whittier Frees (1879–1953).

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TROUBLE SHOOTING

Melting time depends primarily on the frequency at which your microwave oven operates. 

If the marshmallows don't melt, adjust the 'cooking' time to melt the marshmallows. Melting time at full power can take a couple of minutes or more.

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Flow Chart, Math 164, cartoon by Sidney Harris, www.sciencecartoonsplus.com.

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Depending on the frequency at which your microwave oven operates, the resolution given by full-sized marshmallows might be inadequate; if you decide it is, try smaller marshmallows or try cooking chocolate (any other type of chocolate will not burn or melt adequately). Cheese also works.  

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Do your results look like this? Possibly the time was too long, the container too shallow, or the marshmallows too large.

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If your microwave doesn’t have a removable turntable, it means that the turning mechanism is elsewhere and you’ll need to find a regular microwave oven to try this experiment. You may or may not realize that the so-called convection microwave oven is a combination of a standard microwave and a convection oven.

Centimeters provide more precise measurements than inches; measure in centimeters.

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Here's a summary for review.

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EXTRA CREDIT:  BOYLE'S LAW

Do you have any marshmallows left over?  If you do, you can use them to demonstrate the relationship between the volume of a gas and its' pressure!

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Compressed marshmallow placed directly in Sous-vide chamber.

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Place a few marshmallows in a jar, large syringe, or plastic container, seal it, and then pump or squeeze out all the air. Any kind of vacuum pump will do; a plastic kitchen basting syringe works too.

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Watch 'em expand!

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Congratulations! This demonstrates Boyle’s Law, which states that when temperature doesn’t change, the relationship between pressure (decreased by pumping air out of the container) and volume of any set amount of gas (the marshmallow) is inversely proportional. In other words, decreasing one necessitates increasing the other.

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Inversely proportional seesaw kitties, photograph by Harry Whittier Frees (1879–1953).

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Marshmallows are basically a colloid foam, spun out of sugar, water, air, and gelatin. The sugar makes them sweet, the water and sugar combo makes them sticky, and the gelatin makes them stretchy. But the air, which actually makes up most of the marshmallow's volume, makes marshmallows a tasty way to encapsulate a gas in a solid. As you pump air out of the container, the air inside the marshmallow expands and the marshmallow puffs up. Release the seal, and the marshmallows return to their normal size.

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OK, ALL THIS WORKS, BUT WHY?

Are you feeling adventurous? If you're curious about learning more about microwaves and the electromagnetic spectrum, then read on. I've included here some bits here about atoms, elements, chemistry, and the EM spectrum, because matter matters. Enjoy!

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THE ELECTROMAGNETIC SPECTRUM

Learning more about microwaves requires learning bits about atoms, elements and chemistry, so I've included some of these bits in the paragraphs below. Matter matters; enjoy!

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The electromagnetic spectrum (EM) is the name we give to a map of all the radiating energy we can identify that is moving through space; this information is divided and arranged according to the length and frequency of the radiation (wavelength and frequency).  Think of it this way: all this radiating energy is traveling through the vacuum of space at the same speed, as electromagnetic waves, some of which are busier than others while they do it.

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Westinghouse Electromagnetic Spectrum Chart.

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Since matter is composed largely of electrons, the interaction of electromagnetic radiation with electrons is a vast topic of considerable interest and utility. Electromagnetic radiation covers a wide range of frequencies (F), or what is equivalent, of quantum energy (frequency or wavelength times Planck's scale constant). The spectrum includes radio waves, microwaves, infrared, visible, ultraviolet, X-ray and gamma-ray regions.

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"Cum Grano Salis"; don't take this Electromagnetic Spectrum Chart too seriously!

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Various phenomena occur when a wave encounters energy such as a reflection of itself, or another wave, an obstacle, an opening, or a constraint of some kind. Some of the phenomena include reflection, deflection, absorption, diffraction, interference, superposition, resonance, cancellation, transverse polarization, and phase change. 

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Radar emits a burst of energy, the energy strikes an object and is scattered in all directions; only a small fraction of it is directed back, towards the radar. (Photo courtesy of Wikipedia  https://fr.wikipedia.org/wiki/Fichier:Radarops.gif)

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Various models (such as particle, classical wave, and photon models) have distinct 'cum grano salis' application limitations.Wave models used to work with lower frequencies give way to particle models at higher frequencies, but radiation is the same thing whatever the frequency, and is accurately described by quantum mechanics. The most notable consequence of this quantum nature is that energy transfers in discreet units of quantum energy (frequency or wavelength times Planck's scale constant) and these  'quanta' seem to represent the creation and annihilation of  'quanta' or photons. 

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Wave models used to work with lower frequencies give way to particle models at higher frequencies, but radiation is the same thing whatever the frequency.  More Or Less, Math 50, cartoon by Sidney Harris, www.sciencecartoonsplus.com.

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All electromagnetic radiation is composed of massless photons, and in a vacuum, all electromagnetic radiation travels at the same speed. In a vacuum, massless particles don't travel at different speeds; the 'speed of light' is a constant.

Humans visually perceive only a tiny fraction of the electromagnetic spectrum, a portion we call 'visible light'.  However, we commonly use the word 'light' as a generic term meaning any electromagnetic wave. The phrase 'the speed of light' refers to all massless particles.  

By 1873, James Clarke Maxwell had consolidated several important discoveries into four differential equations now known as Maxwell's Equations. These equations describe the relationship between electric and magnetic fields. At some point, the values for a pair of oscillating, self-propagating electric and magnetic fields were plugged into the equations, and quite unexpectedly, the equations produced an electromagnetic wave propagation speed dependent only on universal constants. This speed is the speed of light. So, as the saying goes, Voila! And then there was light! 


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James Clark Maxwell found commonalities by consolidating a large number of discoveries that otherwise appeared unrelated. 

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WAVES

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A wave has a shape with peaks and troughs to it. What we call 'wavelength' is one cycle of a wave, measured as the distance between any two consecutive peaks of the wave. A 'peak' is the highest point of the wave, and the 'trough' is the lowest point of the wave. 

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A wave has a shape with peaks and troughs to it. Chin Up!, photograph by Harry Whittier Frees (1879–1953).

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The number of wavelengths that pass a certain point in a given length or amount of time while traveling is the Frequency (F) of the wave. The number of wavelength cycles that pass per second are measured in Hertz (hz).

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Wavelength, shape with peaks and troughs.

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A longer wavelength means a lower frequency, and a shorter wavelength means a higher frequency. If the wavelength is shorter, the frequency is higher, because in one second of time, many cycles will quickly pass by. Likewise, a longer wavelength has a lower frequency because each cycle takes longer to complete; in one second of time, maybe only one cycle will pass by. All these waves are traveling at the same speed, but some complete cycles faster than others as they travel.  

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Longer Wavelength peaks and troughs.

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"Energetic" waves are traveling with shorter wavelengths, more cycles, and thus have higher frequencies.  "Less energetic waves" are traveling at the same speed as the 'energetic waves' but are taking longer to complete their cycles and thus have lower frequencies.   Again, you can think of it this way: all these electromagnetic waves are traveling through space at the same speed, but some are busier than others while they do it.

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Shorter Wavelength peaks and troughs

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The relationship between the wavelength, frequency,  and speed of a wave is a simple one: v = f•λ.  Velocity, or speed of a wave (also abbreviated by the capital letter C) is equal to the Frequency (F) multiplied by the wave's Length (abbreviated by the capital letter L, or wavelength, or by the lowercase lambda, λ, the 11th letter of the Greek alphabet).  

"Radio waves" are some of the longest wavelengths on the electromagnetic spectrum, and unless you have cable, these are the waves used to broadcast signals to your AM/FM Radio or television. Microwaves are nearly as long and slow as radio waves. Ultraviolet 'light' is part of the spectrum of our Sun's radiation; it isn't visible to humans but that doesn't mean we're immune to a sunburn from it on cloudy day. X-Rays and gamma rays are examples of energetic waves having short wavelengths, high frequencies, and high energy. Compared to them, microwaves are downright languid.

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Wikipedia's animated radar screen sweep; animation simplifiée de l'affichage sur un PPI. (https://en.wikipedia.org/wiki/Radar).

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MICROWAVES

The microwave range of electromagnetic radiation has longer wavelengths and lower frequencies than the visible electromagnetic radiation we can see.  Wikipedia states that different sources define different frequency ranges as microwaves, and that they have wavelengths ranging from one meter to one millimeter,  with frequencies between 300 MHz (100 cm) and 300 GHz (0.1 cm). Wikipedia also states that microwave ovens use a very specific microwave frequency in this range chosen based on regulatory and cost constraints.  (https://en.wikipedia.org/wiki/Microwave_oven).

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Cooking with fire versus microwaves, Food 101, cartoon by Sidney Harris, www.sciencecartoonsplus.com.

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If you look inside your microwave, you will notice that the entire interior is made of metal, either as solid pieces, or as pieces perforated with small holes. There’s usually also a rectangle that juts out from a wall; this is where you’ll find the antenna producing the microwaves. The design is an effective microwave mirror, shielding the outside world from the microwaves generated inside the microwave oven, maximizing cooking efficiency by containing the microwave energy as standing waves inside the microwave oven, and also rotating the food you're cooking so it passes alternately through areas of high and low intensity of the standing wave. The standing wave nodes excite water molecules in food in order to cook the food.  

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Diagram of a standing wave inside a microwave oven.

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An antenna built inside the microwave oven transmits the specific mandated microwave oven frequency, producing a wave contained and reflected inside the oven.  Once inside the oven, this wave is reflected off the walls of the oven. The wave ping-pongs, bouncing back and forth between the inside boundaries.  The wave, and its' reflection, are moving in opposite directions in the same space, and they interfere with each other, creating a   "standing" wave with nodes and antinodes.  Consider this whenever you look at yourself in a mirror!

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Traveling wave interference effects.  Oops! photograph by Harry Whittier Frees (1879–1953).

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Standing waves are formed whenever a wave is reflected back and forth between surfaces n/2 wavelengths apart, where n is a positive whole number.  In a standing wave,  the nodes are a series of locations at equally spaced intervals where the wave amplitude (motion) is zero. At these points, the two waves add with opposite phase and cancel each other out. They occur at intervals of half a wavelength (λ/2). Midway between each pair of nodes are locations where the amplitude is maximum. These peaks are called the antinodes. At these points, the two waves add with the same phase and reinforce each other.

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A sinusoidal standing wave animation, courtesy of Wikipedia. Note the nodes (pun intended)!

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For a sinusoidal wave, the spacing between any node to its' nearest neighbour node, or antinode to its' nearest neighbour antinode, is one half-wavelength.

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Diagram of a sinusoidal standing wave, inside a microwave oven, moving at the speed of light.

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The peaks of a standing microwave heat food faster than the rest of the wave; energy is concentrated at these points.  To heat food evenly, food must be rotated around to evenly expose all the food to the energy from the peaks. As the food rotates around, it passes through these points, and this excites the water molecules in the food, heating the food.

When you heat  marshmallows in a microwave with the turntable removed, the marshmallows can't rotate around and won't cook evenly.  Instead, they'll melt the fastest where they meet the antinodes, the points where the wave amplitude is the greatest. 

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Watch what happens to a marshmallow that doesn't rotate while cooking inside the microwave.

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This makes those points visible in the marshmallows; you can see where they are on what would otherwise be an invisible wave. By making possible a visible measurement of the distance between these points, you create a ‘map’ of the microwaves inside your microwave oven because the distance between any two such melted spots or sections is half the wavelength of the microwaves.  By measuring this distance and multiplying the wavelength by the microwave frequency you found displayed on the back of the oven (mine is 2450 MHz), you can calculate the value of C, the speed of the wave, the speed of light, and often with less than 5% error.

Standing waves also occur in string and wind instruments, and we hear them there, as 'harmonics'. 

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Now let's up the tempo, Math 153, cartoon by Sidney Harris, www.sciencecartoonsplus.com.

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In wind instruments, the nodes occur at fixed ends and anti-nodes at open ends. If the wind instrument is fixed at only one end, only odd-numbered harmonics are produced because at the open end of any pipe, the anti-node is altered by contact with air, and isn't exactly at the end.  

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Marching Band's horn section, photograph by Harry Whittier Frees (1879–1953)

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With string instruments, the density of the string affects the frequency at which harmonics are produced, and the greater the density, the lower the frequency needs to be to produce a standing wave of the same harmonic.

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Marching Band's string instruments, photograph by Harry Whittier Frees (1879–1953).

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ELEMENTAL REACTIONS

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Elements are all pretty much alike, and when combined, what's interesting is that they don't produce a sort of mean between them, like parents produce offspring. 

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Groucho Marx disguised as La Gioconda, the Mona Lisa by Leonardo da Vinci.

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Instead,  nuclei and electrons interact by electrostatic forces, and reconfigure, into structures using the lowest possible energy that we call 'elements', for 'elemental'. There is always a search for lowest energy. 

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Groucho, Harpo, Chico, and Zeppo Marx playing saxophones.

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Elements contain atoms, and their atoms consist of a heavy, positively charged nucleus held together by strong nuclear forces, that holds an equal charge of light mobile electrons tightly around it, so the whole is electrically neutral and doesn't exert strong forces on other atoms. Electrons are all exactly the same; they can be identified only by the quantum numbers specifying a state. Neutral atoms are all roughly the same size, from hydrogen (one proton and one electron) to uranium (92 protons and an equal number of electrons).  Individually, atoms have no macroscopic properties; atoms are the generic building blocks out of which substances are constructed.

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Electrons can be identified only by the quantum numbers specifying a state. An excerpt from the mirror sequence in the film Coconuts, with Groucho Marx.

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When these generic atoms come together, it's often possible to rearrange the electrons, and always the outermost, least tightly held ones so that the resulting electrostatic energy is less than that of the two separate atoms. 

How the atoms behave chemically is determined by the possibilities for the redistribution of charge.  The properties of substances are the properties of associations of atoms, and the nature of the association is more important than the particular atom. 

When different molecules come together, there may be rearrangements of smaller energy, and a reaction may occur.  

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When different molecules come together, there may be rearrangements of smaller energy, and a reaction may occur.   Harpo Marx and Lucille Ball disguised as Harpo Marx.

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Charges of like sign repel one another, so electrons are repelled by electrons and nuclei are repelled by nuclei, but electrons and nuclei attract one another strongly and at large distances. When the total number of electrons and the total number of protons is not equal, the atom isn't electrically neutral and the structured configuration of energy will have either a net positive electrical charge (called a 'cat-ion') or a net negative electrical charge (called an 'an-ion'). Cations and anions will attract each other because of their opposite electric charges, and form 'ion-ic' compounds, like salts. 

In general, when two collections of nuclei and electrons, two systems, come into physical contact, oriented in such a way that a reaction can proceed rather than repulsion, they may rearrange themselves to form a new system of lower energy, dissipating the excess energy somehow, for example by collision or by breaking into two or more parts with kinetic energy. They rearrange themselves at a lower energy, the excess energy is carried away somehow, and we have what we call a chemical reaction. This is the only reason for a chemical react-ion.  

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Excess energy dissipation is the only reason for a chemical reaction.  Harpo Marx's exploding piano, excerpt from the movie A Night At The Opera.

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A chemical react-ion is a process that leads to the transformat-ion of one configurat-ion of chemical substances into another lower energy configuration; it's a change that occurs when two or more energy configurations interact and form a new lower energy configuration. You're a "chemical reaction", and you're "undergoing chemical reactions" all the time.

Chemistry texts still erroneously define a molecule as the smallest amount of any substance that retains the properties of that substance; carbon is considered black, silver as shiny, sulphur as yellow, and mercury as liquid; all these are still wrongly considered properties of the elements. A little energy is required to extract an electron from a sodium atom, a little energy is recovered when the electron sticks to a chlorine atom, and a great deal of energy is released when a lot of these ions associate in a crystal lattice. Salt is this lattice and its' properties, not the properties of any molecule or atom by itself. The textbook definition of molecule has no meaning.

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A great deal of energy is released when a lot of these ions associate in a crystal lattice. Harpo Marx and change, from a pay telephone.

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Most metals are almost alike in nature: they're soft, shiny, heavy, nontransparent substances that can be bent and hammered. They are a pudding of positive ions in a sea of electrons, and their gross properties don't depend on the nature of the ion. Any suitable atom can make a metal. Sulphur doesn't because other sorts of associations give lower energies than a metallic lattice would. Tin exists in both worlds: at higher temperatures tin behaves as a typical metal, but at low temperatures it's a crumbly nonmetallic crystalline substance.

At any given temperature, the minimum free energy is what matters (pun intended) in determining the equilibrium 'stable' state, not just the minimum internal energy, and the entropy is just as important as the internal energy. For example, oxygen molecules attract one another, so minimum energy results when they're all in a heap in the corner. Entropy is what keeps them flying around at room temperature, even at the expense of extra kinetic energy.

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Entropy. Margaret Dumont opens Groucho Marx's stateroom door in the movie A Night At The Opera.

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All binding energy in molecules is electrostatic. A molecule is stable when its' energy is less than that of any other configuration accessible to it. Many textbooks state that "electrons tend to pair"; this is wrong and misleading. The two electrons in H2 are in the same state because all the other possibilities give higher energy. They form a pair out of necessity, not out of desire for one another.  They actually would rather not be so close together, and their mutual repulsion decreases the binding energy somewhat. 

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The two electrons inHform a pair out of necessity, not out of desire for one another. Chico defending himself from Harpo's legs, excerpt from the movie Horsefeathers.

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ATOMIC SOCIALS

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If elemental matter is already at the lowest energy configuration, why change? A configuration located in an isolated system won't change, it's 'stable', but in fact. there is no such thing because nothing is isolated for long - atoms ignore space and time and can travel in a vacuum until energy contacts energy, and when it does, it can change configuration. 

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What's over here is really over there, Astron33, cartoon by Sidney Harris, www.sciencecartoonsplus.com.

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You can think of energy as a Neighborhood moving in timespace, until it interacts in various ways depending on the meeting's 'point-of-view'. The 'neighborhood' has neighbors and tourists and such: other atoms, other nuclei, other electrons, traveling waves, configurations coming from outside the system, all of which offer possibilities for reconfiguration through changes in, for example, pressure, temperature, direction, movement, size, and space.

 

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"Il à la WiFi." He has wifi. Credit: Sonnette.

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CELLULAR MOBILE TELEPHONE EM WAVE REGION

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Mobile cellular phone frequencies use these ranges of the electromagnetic microwave spectrum.

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Radio frequencies allocated for cellular networks to use will differ around the world, however the majority of networks utilize the broadcast carrier frequencies designated 'radio frequencies', and these are between 3 KHz to 300 gHz. The actual frequency used by a particular cellular mobile phone may also vary from place to place, depending on the settings of the carrier's base station.  

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"I thought it would give me better cell phone reception", cartoon by Maris Scrivan.

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MICROWAVE EM WAVE REGION

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"Je connais son astuce;  il utilise un réseau sans fil professionnel." I know his trick; he uses a professional wireless network.

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General Microwave ranges are:
UHF    Ultra high frequency     300 MHz   //  1 m   //  1.24 μeV
VHF    Very high frequency     30 MHz  //  10 m   //   124 neV

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Rabbit bunnies listening to shortwave radio, photograph by Harry Whittier Frees (1879–1953).

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Wikipedia states that different sources define different frequency ranges as microwaves (https://en.wikipedia.org/wiki/Microwave). Quote:
"Microwaves are a form of electromagnetic radiation with wavelengths ranging from one meter to one millimeter; with frequencies between 300 MHz (100 cm) and 300 GHz (0.1 cm). Different sources define different frequency ranges as microwaves; the above broad definition includes both UHF and EHF (millimeter wave) bands....The boundaries between far infrared, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study. Microwaves travel by line-of-sight; unlike lower frequency radio waves they do not diffract around hills, follow the earth's surface as ground waves, or reflect from the ionosphere, so terrestrial microwave communication links are limited by the visual horizon to about 40 miles (64 km). At the high end of the band they are absorbed by gases in the atmosphere, limiting practical communication distances to around a kilometer. 

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Attempts to improve cell phone reception.

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Microwaves are extremely widely used in modern technology. They are used for point-to-point communication links, wireless networks, microwave radio relay networks, radar, satellite and spacecraft communication, medical diathermy and cancer treatment, remote sensing, radio astronomy, particle accelerators, spectroscopy, industrial heating, collision avoidance systems, garage door openers and keyless entry systems, and for cooking food in microwave ovens."

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Kitty falls asleep while listening to shortwave radio, photograph by Harry Whittier Frees (1879–1953).

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Wikipedia also states the following: "The microwave frequencies used in microwave ovens are chosen based on regulatory and cost constraints.... A microwave oven converts only part of its electrical input into microwave energy.... A microwave oven heats food by passing microwave radiation through it. Microwaves are a form of non-ionizing electromagnetic radiation with a frequency higher than ordinary radio waves but lower than infrared light. Microwave ovens use frequencies in one of the ISM (industrial, scientific, medical) bands, which are reserved for this use, so they do not interfere with other vital radio services. Consumer ovens usually use 2.45 gigahertz (GHz)—a wavelength of 12.2 centimetres (4.80 in)—while large industrial/commercial ovens often use 915 megahertz (MHz)—32.8 centimetres (12.9 in)."

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This is not an actual atomic blast.

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I sign our magazine articles "See Into The Invisible". Thanks for reading.

Best Wishes, 
Debra Spencer

All Content is © Debra Spencer, Suit Yourself™ International. Technical Library FAQ Index ISSN 2474-820X. All Rights Reserved. Please do not reproduce in part or in whole without express written consent. Thank you.
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All Content is ©2019 Debra Spencer, Appanage™at www.suityourself.international Suit Yourself ™ International, 120 Pendleton Point, Islesboro Island, Maine, 04848, USA 44n31 68w91 Technical Library FAQ Index ISSN 2474-820X. All Rights Reserved. Please do not reproduce in part or in whole without express written consent. Thank you.

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All Content is ©2019 Debra Spencer, Appanage™at www.suityourself.international Suit Yourself ™ International, 120 Pendleton Point, Islesboro Island, Maine, 04848, USA 44n31 68w91 Technical Library FAQ Index ISSN 2474-820X. All Rights Reserved. Please do not reproduce in part or in whole without express written consent. Thank you.
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