Demo #1Conservation of Energy
Physics can be looked at as a study of energy. Energy makes things happen. It cannot be created or destroyed, however it can be transformed from one type of energy into another. We live with examples of this in our everyday life. In fact, the application of technology that has become a part of our everyday life is just the manipulation of energy in one form and turning into another. Oil has a chemical energy which we turn into heat energy and the energy of motion which is called kinetic energy. A simple demonstration of energy conversion can be shown with this hanging bowling ball. First we see that a moving bowling ball can knock down a wall. That is because a moving object has kinetic energy. We also know that when an object on earth is raised to a height and released it will fall. That means it must have energy because if we let go of it, something happens. This energy is called gravitational potential energy and it is changed into kinetic energy once the object is released. So by raising this bowling ball pendulum and releasing it we see one form of energy being turned into another over and over. Gravitational potential energy is turned into kinetic energy which is converted back into gravitational energy which is changed back to kinetic energy. Now if I stand here and put this ball to my face and release it, we can see a death defying feat! The Smashing face demo! All is well. The bowling ball didn't come back and hit me in the face! This is due to a very fundamental physics law call Conservation of Energy. As stated before, energy cannot be created or destroyed so I know that the ball will not gain energy after I release it so the ball cannot go higher than its original release, so I know it will not hit my face!
Demonstration Notes:
To
hang a bowling ball first start by drilling a hole into the ball and either tap
a thread into the ball and screw an eye bolt into the threaded hole or drill a
hole and use an eye screw if threading is not possible. Hang the ball from a strong support
with rope or a cable. 
Attach to the support so the pendulum moves with minimal friction. Best to have where the rope or cable connects to the support such that it does not move or rub on the support. The wall I use to knock over is a bunch of cardboard boxes that look like bricks. John Gellagos aty University of New Mexico set-up a great wall of long cardboard packing tubes with coffe cans stacked on top. It makes a great noise when knocked over! Definately a crowd pleaser! Knock anything over that can show there
is energy in the moving bowling ball. When releasing the pendulum in front of
your face, place the back of your head against a wall or maybe a step ladder if
you are at center stage. You want
to make sure your head does not lean forward upon releasing the bowling
ball!! We have a natural tendency
to do this! It also looks more dramatic when the ball is coming back at your head if there is a support behind your head. Also DO NOT
give the pendulum a push when releasing the ball! If hanging a bowling ball is not possible, try using a small steel ball pendulum and a crystal glass instead of your face.
Demo #2 Energy Transfer: Particle Interaction
We live in a world where collisions happen at every moment. On the microscopic level, molecules collide with each other and on macroscopic objects. The yielding effect of this is air pressure! We also have big collisions, such as billiard balls on a pool table or the unfortunate car accident. When I release this bowling ball, it now collides with the smaller bocci ball. Some of the energy of the bowling ball is transferred to the bocci ball and it obtains kinetic energy that is turned into gravitational potential energy. This type of energy transfer, performed by two objects interacting with each other, can be referred to as a "particle interaction". We can also see particle interaction with a Newton's Cradle or by the interatcion of two billiard balls.
Demonstration Notes:
Hang the bocci ball the same way as the bowling ball and align it so the centers of the ball interact. (The bocci ball can be set to the side when you are doing the first demo.) Be sure to have an assistant watch where the balls go once they collide. They can go off to one side or the other so make sure they will not hit other demos on the staging area. You could also do this with two bowling balls. You can usually find cheap bowling balls at a local Goodwill, Salvation Army, or other second hand goods store. You can also do particle interaction demonstrations with billiard balls on a tabletop, or use a Newton's Cradle apparatus. (For example http://store.thetech.org/newtonscradle.html). The billiard balls can also be used if it is too difficult to safely hang the bowling and bocci balls.
Demo #3 Energy Transfer: Waves
We have seen that objects colliding can transfer energy. If an object is thrown into a body of water it produces waves. These waves move along the water and we can observe that a stick floating on the water a distance away will move up and down once the waves reach it. The stick gains a vertical kinetic energy form the wave. The energy of the object hitting the water created waves and these waves transfer some of the energy to the stick. My assistant from the audience is holding the end of this long spring and bell. Observe what happens when I wiggle the my end of this long spring. Waves are created and these waves move along the spring and makes my assistant's arms wiggle up and down making the bell ring. The energy is transferred by the wave motion. Notice the characteristics of the wave. The material between the ends only moves in the vertical direction and does not move in the horizontal direction. This is called a transverse wave. You can see waves produced by an object making sound when a tuning fork is placed in dish of water,. The vibrating tuning fork produces waves and the energy is transferred to other parts of the water tank. Vibrating objects produce pressure waves in air and these waves are called sound waves. My voice gives energy to air molecules which vibrate back and forth producing the wave of varying pressure, and this wave transfers the sound energy to your ear drum, which vibrates, and you detect and therefore hear my voice.
Demonstration Notes
Some basic demos that show how waves transfer energy are employed here. The long spring works great for transverse waves and slinky for longitudinal waves. I have also made a long rope made from Lycra which works well on a big stage and you can contact me if you would like more details. I sometimes skip longitudinal waves since it is not necessarily important to my final goal in this show. I have also done waves with people holding hands, similar to waves in a stadium. A row of people come on stage and I hand out glow sticks and have them hold hands and send a wave along and the person at the far end has a bell they ring when the wave gets to them. Great for more audience participation and it looks cool with the lights out. The tuning fork in water is done using a Pyrex baking dish on an overhead projector so the audience can see the waves.
Demo #4 Wave Phenomena
A wave frozen in time is modeled with these copper tube waves. Waves have a physical length that is called the wavelength. They vibrate and the time for one complete oscillation is called the period of the wave. How many times the wave vibrates each
second is called the frequency.
Waves also travel at a speed that is found by multiplying the wavelength
times the frequency. Waves from
sound travel at a particular speed (340m/s in air) and have the relation where
the higher the pitch of the sound, which relates to the frequency, the shorter
the physical length of the wave.
Observing what heappens when two waves interact we can see some interesting physical properties. Using these two wave models we see that they can interact and add together to make a bigger wave or cancel out making a smaller wave. We call
this constructive or destructive interference. We can demonstrate how sound waves can interfere with each other using the Dr. Seussophone Sound Interference Demonstrator
(pictured with original builder Sam Sampere University of Syracuse). Sound travels through two different paths and come back together and mix at the horn output. We can change the length of one path by
moving the pipes up much like a trombone.
Notice that as the top half path length changes the sound gets louder and softer. This is due to the waves
adding or canceling each other out. If the top half pipe length is related to one half of the wavelength of the sound, then a wave trough (low pressure part of the wave) interacts with a crest (a high pressure part of the wave) resulting in a lower sound intensity. If the upper pipe length is related to the wavelength, the crest and troughs will line up to make a larger wave resulting in a higher sound intensity.
Demonstration Notes:
Copper tubing bent into the shape of a sine wave works for discussion of wave characteristics. I first saw the pipe sound interferometer in a demonstration by Sam Sampere at the WYP organizational meeting in Montreal Canada. The picture shows it in use and I have included a web reference (http://hendrix2.uoregon.edu/~demo/Seussophone/) for instructions on how we built our apparatus. You can also do sound interference with two speakers connected to a signal generator. Set the frequency for around 800 hertz. Have the audience plug one ear and move their head from side to side, or move one speaker to change on of the path lengths to thier ear, and they will hear the sound get louder and softer. The idea is to build some background to enable a demonstration of the wave property of light interference. You could also change the phase of one speaker, essentially flipping one of the sound waves, by having a reversing switch connected to one of the speakers. The sound will then be canceled in the two speakers are close to each other. I refer you tio the DVD to see this demonstration in action.
Demo#5 Electricity
We can get electrical energy by rubbing objects together. This happens with clothes tumbling in a dryer or walking across a carpet and getting a shock when touching a door knob. These are examples of static electricity. This is caused when rubbing objects move electrical charges from one object to another. There are two types of charges, one is called negative and the other is positive. Unlike charges attract and like charges repel. We can separate electrical charges creating electrical energy with a Van de Graaf generator. It has a rubber belt that moves over a roller where the roller interacting with the belt causes charges to gather onto the belt and the moving belt transfers the charges to the top dome. We can observe the electrical force and observe like charges repelling using packing peanuts. (A container of Styrofoam peanuts is placed on the top of the dome. Activating the Van de Graaf will make the peanuts float away. Like charges repel each other.) If a person electrically insulated from the Earth touches the dome, the charges will gather on them. A volunteer from the audience is needed. We can see that when I energize the generator the hair on (volunteer's name) head stands up! This is because these like charges are trying to get as from each other as they possibly can. Oh yes, and there is energy as you can see the person jump if a spark occurs! This energy called electrical potential energy is directly related to what we all call voltage. Notice if I put charge on this electroscope, the needle moves. This again is due to the charges trying to get as far from each other as they can. Touch the electroscope and the needle goes back to its neutral position because the charges come onto me and reach the Earth which, being a large object, is able to store a lot of charge. Electrical charges entering or leaving the electroscope are observed by the resulting needle movement.
Demonstration Notes:
Be sure the Van de Graaf, is working before the show. I advise packing a hair dryer to blow dry the thing before the show, especially if it is getting humid. All Styrofoam peanuts are not the same! Try a number of varieties until you find some that work. The container holding the peanuts should be plastic although a very shallow pie pan will also work. Styrofoam blocks can make a good low cost insulating stand for charging a person and making their hair stand up. A volunteer with thin medium length hair usually works well. Red hair seems to be thinner and therefore seems to work best. The idea is to build up the idea of electrical charges and also showing how the electroscope works for the photoelectric effect demonstration.
Demo #5 Light and Color
White light is made up of a full spectrum of colors. The color of light is characterized by its frequency or wavelength. Red has a lower frequency than green which is lower than blue which is lower than violet. ROYGBIV is listed by low frequency (long wavelength) to high frequency (short wavelength). This is also listed in the order of low energy to high energy. A prism separates light into its fundamental colors, red ,green, and blue. These are the three colors that our eyes are able to detect. There are also frequencies of light our eyes cannot detect, but other instruments can. Light below red is called infrared and above violet is ultraviolet. We can use this special camera that is sensitive to infrared light that we cannot see. Look at the spectrum from the prism with the IR (infrared) camera and we notice that it is wider than what we see with our eyes. Placing this IR filter (blocks visible light but passes infrared) in front of the prism, we see the spectrum our eyes see disappears, but the camera can still see a band of light. This is infrared light. It is also a part of the white light spectrum, but we cannot see it.! We will look at these forms of invisible light later, but first, does light energy travel as a wave or a particle?
Demonstration Notes:
To see the spectrum from a prism requires a line source of light. This is possible using light from a slide projector with a slit slide in it. A slit slide can be made easily by placing aluminum foil inside a slide mount and cutting a very narrow slit in the foil. Put the slit slide into the projector and place the prism in front of the slide projector lens and rotate it until you see the spectrum. Focusing will make the colors sharper. You can also make a line source by putting two pieces of paper close together on an overhead projector and build a small holder out of foam core that will hold the prism on the head of the transparency projector. You could also use a good holographic diffraction grating instead of a prism with either set-up to obtain the spectrum of colors. The diffraction grating will require a darker room to see the colors. You can use the IR camera and the IR filter and see that there is infrared light coming from the projector.
Demo #6 Light as a Wave
We can show a light path using the fog machine. When a light beam hits the vapor it scatters off of the vapor particles and our eyes can then see the path of the light. It is a very interesting observation that light can only be observed when it interacts with something, we don't actually see it while it travels, only when it hits something. There is a lot of light traveling in space, but space is dark. We only can determine that light is traveling when it interacts with something, like sunlight hitting the moon! This is a very fascinating aspect of light that can send your head thinking! (Darken the room and using a green or red laser pointer show how they can se a dot on the wall but cannot see the light traveling from the pointer to your hand. Turn on some "cosmic" music. I use Pink Floyd Time form Dark Side of the Moon, and start up the fog machine. The beam will become vsible and you can move it around making a primitive laser light show.) We saw earlier that sound traveling two different paths can interfere such that the sound can be louder or softer depending on the path length. If we see this phenomena with light than we can assume the energy travels as a wave. We have a device called an interferometer that can send light onto two paths and then recombine the light onto a screen. The fog vapor displays how the light is split and recombines and travels to the screen. With the addition of a diverging lens, we see there are dark areas and bright areas! Light energy must travel like a wave! But what is vibrating, there is no air in the vacuum of space but yet sunlight makes it to the Earth. Actually, what is changing is the intensity of electrical and magnetic energy, but that is another lecture. We can see with the results of this interferometer that light energy travels as a wave.
We can also show the wave properties of light using a grating which is simply a bunch of lines on a transparent piece of material. Here light travels between the lines so this acts as a large number of light sources acting together. The light coming from these sources interferes and we get areas of bright light where the light waves add together. A diffraction grating also suggests that light energy is traveling as a wave. (The light rays from a grating can be seen quite nicely in a darkened room using the fog machine. A real crowd pleaser.)
Demonstration Notes:
Plans for a low cost
interferometer can be found at the LIGO web site. http://www.ligo-wa.caltech.edu/teachers_corner/lessons.html and a parts list can be found at: http://zebu.uoregon.edu/~rayfrey/QNet/IFO_parts.html I utilize a video camaera connected to a video projector to display the bullseye light pattern from the interferometer. 
Using the holographic diffraction grating available from
Project Star (http://www.starlab.com/psprod.html#Anchor-Holographic-35882) with a laser pointer is a cheaper and easier way to go. A laser pointer can be used for all these demos. If you
have it in your budget, a green laser pointer is much more visible. (for
example http://www.z-bolt.com/generic27.html) A relatively cheap fog machine can be bought at http://www.coolstuffcheap.com/fogmachines1.html but you can also use chalk dust from an eraser, fog from dry ice in water or spraying a mist from a bottle. I like to digress about how light has to interact with something to be observed as an example of its interesting properties.