Exploratorium Exhibits - Rental Group C

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					Exploratorium Exhibits - Rental Group C
 234 - Aether Zoetrope
                                  The Zoetrope was invented in the mid-1800’s, long before the development of the
                                  movie camera and animated cartoons, as a way of deriving motion from still pictures.
                                  Look through the slits at the drawings and turn the crank at the side of the exhibit
                                  as fast as you can. Turn the crank the other way and notice that the balls roll in the
                                  opposite direction. As the cylinder rotates, you see a fragment of the picture on the
                                  far side of the cylinder. When the next slit passes your eye it reveals a slightly
                                  different part of the picture. Each image lingers in your eye and brain long enough
                                  to merge with the next image. This phenomenon, called persistence of vision,
                                  creates the illusion of a continuously moving picture.

 001 - After Image
                                  With Afterimage, visitors experience the way an image stays with us long after we
                                  have seen it. Visitors look into the viewer and push a button, causing a bright
                                  strobe light to flash behind a slide with images of a circle and a cross. These patterns
                                  are visible for up to fifteen minutes. Remarkable color changes, shape disintegration,
                                  and movements can also occur during the life of the after-image.

 003 - Aurora
                                  Aurora shows how reflections are created by both the shape of the light and the
                                  shape of the reflector. This reflector is a large curved sheet of brushed stainless steel.
                                  The ridges in the steel act like tiny mirrors, each reflecting an image. When the
                                  images from all the ridges add up, they blend into a single elongated image that
                                  looks like a ribbon of light. The many-colored tiles of the exhibit allow visitors to
                                  experiment with both the shape and color of the reflections.

 406 - Bicycle Legs
                                  Bicycle Legs is a mechanical representation of human legs applied to the task of
                                  pedaling a bicycle. Each leg is powered by two air cylinders, which represent the
                                  two major leg muscles. Visitors can activate each of the four cylinders separately. By
                                  carefully timing the activation of the cylinders, it is possible to set the legs to
                                  pedaling. With a little practice, visitors can get the legs pumping by using only two
                                  of the air cylinder muscles.

 008 - Blood Vessels of the Eye
                                  Blood Vessels of the Eye reveals to visitors the tiny blood vessels that carry
                                  nourishment to the retina. Even though these vessels are always in our field of
                                  vision, we normally don’t see them because the brain, coupled with fatigue of the
                                  eye’s receptor cells, eliminates them from view. In this exhibit, visitors press a small
                                  penlight against their closed eye lid and move it around. Any light entering the eye
                                  must pass through the blood vessels to reach the retina, casting a shadow on
                                  everything we see. If the penlight continues moving, the eye can’t adapt to the
                                  image, and dark reddish lines (like tree branches) will appear which are actually the
                                  shadows of the eye's blood vessels.

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Exploratorium Exhibits - Rental Group C
 175 - Blue Sky
                                 Blue Sky shows why the sky is blue. This is a phenomenon called “Rayleigh
                                 scattering”. A clear tube is mounted in front of a light source with the light shining
                                 into the end of the tube. The light scattered by the tube looks blue near the
                                 projector and gets progressively yellower further down the tube. A very orange
                                 “sun” emerges from the tube and is projected onto a screen on the side of the
                                 exhibit. A polarizing filter is attached to the exhibit table so the user can experiment
                                 with the polarized properties of scattered light.

 079 - Bone Stress
                                 There are two bones in this exhibit; one is a real human femur and the other is a
                                 plastic model of a human femur. The bones are identical in dimension, and the
                                 human femur is displayed in cross-section so that it is possible to see the inner
                                 structure of the bone. By pulling down on a lever, weight is placed on the plastic
                                 model bone, allowing visitors to see the stress areas in the bone very clearly.
                                 Ultimately, it is shown that the actual bone has developed most of its strength and
                                 structure in exactly those areas of highest stress.

 009 - Bridge Light
                                 Bridge Light lets visitors make interference patterns out of thin air. Two glass plates
                                 form a sandwich with a thin layer of air in between. By pressing on the top plate,
                                 bright and dark bands spread out in a swirling pattern. A bright band appears
                                 wherever light waves reflecting from the back and front surface of the air film
                                 between the plates coincide; a dark band appears where the light waves cancel each
                                 other out. The light source is a sodium vapor lamp and produces a pure yellow light
                                 of similar wavelengths, making visible the interference patterns that are not visible in
                                 white light, with its mixture of different wavelengths. The exhibit also illustrates
                                 absorption and reflection. Several brightly colored cards look dull under the sodium
                                 light, but appear in full color under white light.
 015 - Color Removal
                                 In Color Removal, a light shines through a prism and is spread out into a spectrum,
                                 while the remaining light goes directly to a white screen. By placing filters in the light
                                 path, visitors can observe the unseparated mixture of all the colors in the light that
                                 hits the screen. The constituent colors in the light that goes through the prism are
                                 also visible. Each filter removes (absorbs) some of the colors from the beam of light.
                                 The spectrum shows what colors are removed and what remain. The filters are made
                                 of organic dyes which absorb some of the wavelengths of visible light.

 118 - Color Table
                                 Color Table consists of a number of colored graphic displays, painted surfaces, and
                                 objects. Red, green, blue and yellow hand-held filters are placed around the table
                                 for visitors to use to look at the various objects. When visitors look through a red
                                 filter at a graphic containing greens and blues, only very dark shades of gray will be
                                 seen. One graphic is written in a series of crayon colors. When viewed through the
                                 red filter, the reds, yellows, and oranges disappear, leaving behind the secret
                                 message written in blues and greens. Another station shows a black box with an
                                 even darker hold. Visitors discover that the inside of the box is white and the hole
                                 looks black because light that enters the box is absorbed.

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Exploratorium Exhibits - Rental Group C
 021 - Corpuscles of the Eye
                                 Corpuscles of the Eye shows visitors the blood cells of their own eye. By looking
                                 into a special cylinder, bright sparkles are visible that move with the human pulse
                                 against the blue light. These sparkles are the red corpuscles in the blood vessels that
                                 bring nourishment to the retina. It may even be possible to see these blood cells on
                                 a foggy day, but the blue light in this exhibit makes them especially easy to see.

 682 - Count the Bounces
                                 This exhibit demonstrates the way that attention affects what we do and do not see.
                                 The visitor watches a short video of a group of people bouncing and passing balls
                                 to eachother and is asked to count the bounces. At the end of the video the visitor
                                 is then asked how many times the ball bounced and if they noticed anything
                                 "strange" happen. Upon watching the video again the visitor will discover that they
                                 completely missed a very strange and seemingly obvious occurence due to the
                                 distraction of counting the bounces.

 220 - Delayed Speech
                                 This exhibit delays your words so that you hear yourself talking a fraction of a
                                 second after you've spoken instead of while you are speaking. One or two people
                                 can talk into microphones and hear themselves in headphones. The playback of
                                 their voices is delayed up to 1/5 of a second (variable). This delay makes it almost
                                 impossible for some people to speak intelligibly, since the normal mouth-to-ear feed
                                 back mechanism has been tampered with.

 024 - Diffraction
                                 In Diffraction, a small bright light is mounted behind a hole in a darkened wall.
                                 When looking at the light, it seems to twinkle. This effect is caused by the bending
                                 of light in the eye and its lens. This same diffraction effect is observable in other
                                 objects by using the various props at the exhibit. A diffraction grating bends the
                                 light enough to produce rainbow effects. There are also some common objects, like
                                 a piece of screen, which afford a view of the diffraction patterns caused when light
                                 bends around edges.

 477 - Elastic Surgery
                                 Visitors sit down and position their face in front of a television monitor. While
                                 looking at their face, they have the option to press one of 24 buttons and perform
                                 surgery on their face. Different buttons have different video effects, such as twisting,
                                 pulling, and distorting (images similar to what one might experience at a carnival fun

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Exploratorium Exhibits - Rental Group C
 211 - Floating Rings
                                 This exhibit creates a very convincing illusion in which three brightly polished rings
                                 seem to roll around in marvelous synchronization, like coins spinning on a tabletop,
                                 with their edges always managing to meet perfectly as they turn. A push button will
                                 stop the rings' rotation temporarily.

 330 - Garden of Smells
                                 Dealing with the topic of chemistry is often difficult in a science center environment.
                                 Garden of Smells is a simple exhibit showing people that they have a wonderful
                                 chemistry laboratory in their noses, capable of detecting subtle differences in the
                                 physical structure of molecules.

 404 - Hearing Range
                                 How high or low can you hear? A tone is played through a set of headphones.
                                 The visitor can adjust the frequency of the tone (which is displayed on a digital
                                 counter), testing how high or low a frequency he or she can hear. A person's high
                                 frequency range varies with age, exposure to loud environments, etc.

 326 - Hoop Nightmares
                                 At Hoop Nightmares, visitors shoot a small basketball through a hoop with and
                                 without wearing prism glasses. The glasses shift the visual field, making it difficult to
                                 shoot on target. With five or six practice shots, the eye-brain connection adapts to
                                 the shift, and it is once again easy to sink a shot. Upon removing the glasses visitors
                                 once again lose their shot and must readjust to get back on target.

 036 - Light Island
                                 At Light Island, visitors can play and experiment with various aspects of optics. From
                                 a 200-watt light source in the center of the table, beams of white, red, green and
                                 blue light created by color filters, radiate out onto the table. Mirrors, lenses, prisms
                                 and filters can be placed in the path of these beams to reflect, bend or mix the light
                                 in many ways.

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Exploratorium Exhibits - Rental Group C
 040 - Magic Wand
                                 There’s really no magic at work in the Magic Wand. A lens in a projector produces a
                                 real image in space. Waving the wand provides a surface on which the image can
                                 reflect, so that light can penetrate the eye. Persistence of vision--the eye’s capacity
                                 to retain an image for a short period of time--lets visitors see the individual reflections
                                 from the stick as one whole picture. There are also other images in space found by
                                 waving the wand closer to or farther away from the projector, but only one image is
                                 actually in focus.

 403 - Pitch Switch
                                 In this exhibit, you can raise and lower the pitch of your voice by more than one
                                 octave without changing the tempo. When you speak into the microphone you
                                 make the air around the microphone vibrate. An electronic circuit picks up the
                                 vibrations, changes the frequency, and then sends the result to the earphones.
                                 When you turn the pitch control higher, the circuit increases the frequency of the
                                 vibrations. When you turn the control lower, the circuit decreases the frequency of
                                 the vibrations. To raise the pitch of your voice by an octave, the circuit has to
                                 double the frequency of the vibrations you make.

 048 - Pupil
                                 In Pupil, a lens which is silvered on the back side lets visitors observe their own eye.
                                 There is a light to the side which can be adjusted in intensity from bright to dim. As
                                 the light is adjusted, visitors can observe as their pupil becomes larger and smaller as
                                 the iris dilates and contracts in relation to the intensity of the light.

 266 - Push Over
                                 This exhibit demonstrates how visual clues in the surrounding world help us keep
                                 our balance. Standing on one leg, a striped board suspended from the ceiling is
                                 slowly moved to the left. As the vertical lines move you try to compensate for their
                                 motion, slowly throwing yourself off balance.

 049 - Rainbow Edges
                                 Rainbow Edges demonstrates a phenomenon that has always been a problem for
                                 astronomers and camera makers -- the tendency of lenses to make rainbows out of
                                 white light. In part one of this two-part exhibit, the visitor can see the fuzzy
                                 rainbows around lights caused by the lens in his or her own eye. By looking at the
                                 purple H, the visitor sees either sharp red dots surrounded by fuzzy blue halos, or
                                 blue dots with red halos. The eye's lens bends more blue light than red, so it can’t
                                 focus both colors on the retina at the same time. Normally, inhibition eliminates
                                 these rainbows from view, but because red and blue are at opposite ends of the
                                 spectrum, they are too far apart to inhibit each other. Observable also is the
                                 chromatic aberration of a lens. A colorless screen of dots, seen through the lens,
                                 produces colored spots. The lens bends different wave-lengths of light at slightly
                                 different angles, which accounts for the rainbow effect.
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Exploratorium Exhibits - Rental Group C
 389 - Repeating Words
                                 Repeating Words demonstrates a sound illusion. Through earphones, listen to a
                                 word or series of words repeated over and over with no pause in between them.
                                 Notice what word or words you hear, then find out what you have been listening to
                                 by looking under the sign "Repeating Words." You will find that you can hear
                                 sounds that are not there. These illusory words are heard quite clearly and it is hard
                                 to believe that you have not actually heard them. Repeating sounds quickly loose
                                 their context. As you look for meaning in a situation, you come up with different
                                 interpretations of what is being said.

 327 - Selective Hearing
                                 At Selective Hearing, two separate recordings play at the same time, one coming
                                 from a speaker on the right, and the other from the left. Listening to one message
                                 makes the other seem to move into the background. Looking at one speaker will
                                 bring its message to the foreground. The exhibit highlights the process of listening
                                 to one conversation while excluding others at, for example, a cocktail party. The
                                 sorting out occurs in the brain, not in the ears themselves, but the mechanism is not
                                 entirely understood.

 064 - Spectra
                                 Spectra allows visitors to play detective, examining the “fingerprints” of elements in
                                 the form of spectra. The exhibit provides gas-filled tubes of Argon, Mercury vapor,
                                 Neon, Nitrogen, Helium and Xenon. As the exhibit’s pointer is turned, a different
                                 element lights up. The emission spectra of the various gases may be examined by
                                 selecting a particular gas and viewing it through a diffraction grating.

 349 - Spinners
                                 The visual system adapts to spinning motion in Spinners. When visitors first stare at
                                 a spinning spiral, it appears to move in and out. By continuing to stare for 15 or 20
                                 seconds, one set of motion detectors in the eye becomes tired, and the motion of
                                 the spiral appears to stop. By looking away from the spiral at something stationary,
                                 the opposite set of motion detectors takes over and visitors will briefly see motion in
                                 the opposite direction. The visitor can also experiment with a pattern of rotating

 335 - Stereo Sound
                                 Stereo Sound consists of a vacuum cleaner hose bent into a U-shape with an
                                 earpiece at each end. One visitor holds the earpieces up to his or her ears while
                                 another visitor taps the hose with a stick. When the tap is off-center, most people
                                 have a very clear sense that the sound comes from one side of the head or the
                                 other, although the sound comes to both ears. Even though the time delay is very
                                 brief, our ear-brain system can detect it. This demonstrates how we are able to
                                 locate the sources of sounds as accurately as we do.

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Exploratorium Exhibits - Rental Group C
 613 - Television Snow & Radial Edges
                                 Television snow is usually very boring. We change the channnel. In this exhibit, the
                                 snow is alive and seems to run in circles around the straight lines. Since the snow
                                 dots are constantly going off and on, this pattern helps the snow "move" around
                                 the straight lines, even though the dots are only blinking.

 351 - Tone Memory
                                 Are you tone deaf? Do you have perfect pitch? This exhibit demonstrates the
                                 surprising difficulty of remembering and matching a musical note. The visitor is
                                 provided with a reference tone as well as a second tone which can be adjusted with
                                 the use of a knob. The challenge is to hear the reference tone and then match the
                                 frequencies of the two tones based on the memory of that first tone. When
                                 listening to the tones together, one can hear fluctuations in loudness called beats.
                                 The greater the number of beats per second the farther apart the two tones are in
                                 frequency. These beats help musicians tune their instruments by enabling them to
                                 detect tiny differences in pitch by ear and make the appropriate adjustments.

 069 - Trapezoidal Window
                                 A window frame in the shape of a trapezoid rotates on a pedestal. By watching it
                                 from a distance, it appears to swing back and forth in alternating rotations of 180º,
                                 rather than continually spinning a full 360º. This occurs because we are, in our
                                 civilization, surrounded by rectangular structures; hence when we are presented with
                                 a rotating trapezoidal object which has all the usual features of a common
                                 rectangular object, we are strongly inclined to see the smaller end as being further
                                 away. It is easier to believe that the rotation is reversing than to believe that the
                                 smaller end is actually getting closer.

 676 - Velvet Hands
                                 Keeping their hands pressed gently together, visitors lightly rub a large wire
                                 mesh disc between their hands. Some people experience a strange velvety
                                 sensation when they do this. Visitors can try the smaller velvet or mesh disk
                                 for comparison sake.

Prepared on August 23, 2002