What are overhead projector Sheets called?

On the crest of 'wave ...

August 29, 2013 – 00:48

CWC visual painting guide - PICTURE HEAVY - NerfHaven

The 'ripple tank is a tool that allows you to easily study wave phenomena. As seen in the figure, it consists of a tray with a bottom made of transparent Plexiglas, elevated above the laboratory bench with metal legs, it is poured into water, then surface of the liquid is at a horizontal metal rod supported by elastic , above which is mounted a motor with eccentric mass. Here the device is unplugged and is resting on the laboratory bench, waiting to be used. As can be seen in this photograph taken by my boys as 4 D 2003/2004, now the ripple tank has been connected to: the motor that vibrates the wand horizontally (vibrator) is powered at 5 V DC, while the lamp el 'shutter which rotates in front of it are supplied at 220 V in alternating current, when the motor is rotated, it swings out due to the mass center of gravity and produces the waves on the water surface. But how do you view them? The trick is soon revealed. Above the tank is placed a projector, in front of which a fan wheel that acts as a shutter, so it acts as stroboscope. By adjusting the current that powers the motor of the vibrator and the shutter, you can run them with the same frequency, then the waves projected on the counter still appear, and you can draw them on paper and measure eg. the wavelength by means of the ruler. This photograph, taken instead by Roberto Carettoni (II B cl. As 2004/05), shows a further detail taken from the strobe. As you can see, the fan interrupts the beam of light allowing easy viewing of the waves in question. The principle is the same as the strobe lights of a nightclub. This one particular always taken dall'alunna Chiara Riot, instead illustrates the procedure to display the phenomenon of reflection in the water pan is placed a straight metal bar that acts as a mirror plane. This photo appears in the foreground and also the vibrator motor with eccentric mass that puts it into action. Here is the result of a first observation of the phenomenon previously discussed: on the white sheet you can see the plane waves reflected from the metal bar (the picture is of the IV D as 2003/04). Bringing everything on paper is easy to verify that the angle of incidence appears congruent angle of reflection, as studied theoretically in the classroom. Another picture of Roberto Carettoni showing another spectacular phenomenon: with a rod curve of parabolic shape is possible to observe the plane waves which become spherical and are concentrated in the fire, in agreement with the properties of the parabola studied in the course of Mathematics. Here then is linked to car headlights and satellite dishes on the rooftops. Inserting in the vibrator plan an appropriate firing pin which ends with a ball of plastic or metal, is observed directly the formation of spherical waves (in the specific case, because circular two-dimensional), it can measure the wavelength and can transform plane waves with parabolic mirror. This is the work of IV D as 2003/04. E 'then can insert in the vibrator floor two strikers ball, which generate circular waves in phase with each other (ie, having the same period, the same amplitude and the same phase), which will give rise to the phenomenon of interference. We observe clearly the destructive and constructive interference fringes, having both the shape of equilateral hyperbolas. In reality, the physics of waves that propagate in the water is very complicated, since their propagation, used (such as nell'ondoscopio) as a prime example of wave phenomenon, is very different from that of the sound waves or light. To study the propagation of waves in the sea can be a great help Google Earth , the popular program that offers images of the Earth from space. Observe such qusest'immagine ... ... And this one, which represent an inlet of the Mediterranean Sea at Alexandria (the coordinates are 31 ° 12 '28.56'' N, 29 ° 53' 34.66'' E). The above was taken on 20/9/2010, the one on the right on 14/12 next. In both it is easy to recognize the phenomenon of diffraction: the plane waves that affect the mouth of the bay are transformed into spherical, because the inlet has a dimension comparable with their wavelength! This third example of educational usage of Google Earth shows the same phenomenon, this time resumed 14/12/2010 in Theoule-sur-Mer in the south of France (43 ° 31 '54.86'' N, 6 ° 56' 59.41 ' 'E): the barriers of the ports and beaches (very evident here!) transform plane waves arriving parallel to the coast in circular waves, causing beach erosion feature in the shape of a semicircle! The beach erosion due to spherical waves diffracted by the barriers of protection is particularly visible in Campo di Mare in the province of Brindisi (coordinates 40 ° 32 '27.33'' N, 18 ° 04' 17.09'' E, photo taken on 14 / 12/2010). The breakwaters have literally changed the shape of the coast, allowing to greatly expand the surface of the beach. In this way, each student can realize how the waves can get around the obstacles. This particular greatly magnified by a ship near the southern coast of Cyprus (coordinates 34 ° 56 '27.21'' N, 33 ° 39' 17:36'' And, photo taken on 7/7/2007 is another outstanding example of how, through the phenomenon of diffraction, waves can turn around obstacles they encounter. This explains why we can hear about a person, even if it is in another room: his voice around the edge of the door! Latest example of diffraction of waves: these breakwaters in La Grande-Motte, in the region of Languedoc-Roussillon, France (43 ° 33 '18.71'' N, 4 ° 05' 01.20'' E, taken on 21/8 / 2006). In addition to this characteristic semicircular erosion of the beach, here you can see the waves of the Mediterranean around the breakwater, and reach every corner of the beach! Here we see a different phenomenon, the 'interference between wavefronts generated by circular openings in the protective barriers of the beach. We are located in Rimini on 05/28/2002 (coordinates 44 ° 05 '15.02'' N, 12 ° 32' 26.07'' E). You can also observe the phenomenon of the reflection of circular waves on the beach, the waves reflected, in turn, interfere with those entering through the barriers, making it very difficult to properly describe this wave. The phenomenon of interference between the spherical waves in phase between them is even better seen in this satellite photos depicting the coast in front of Bangkok, capital of Thailand (coordinates 13 ° 36 '40.11'' N, 100 ° 34' 46.60 ' 'E), picked up by satellite on 4/11/2010. The overlap of a ridge with a throat tends to cancel the wave (destructive interference), while the overlap of two ridges or grooves of two amplifies the (constructive interference). The phenomenon of reflection of the waves (in addition to the diffraction) is clearly visible in Port Elizabeth in South Africa, in this photo taken on 24/2/2007 (coordinates 33 ° 57 '19.98'' S, 25 ° 38' 33.05 ' 'E). The yield spherical wave from the breakwater be an impact on the beach, and this is reflected back in the form of a spherical wave whose center of propagation seems to be beyond the obstacle. But here we are in London on the Thames, in December 2006 (coordinates 51 ° 29 '42.06'' N, 0 ° 03' 37.86'' E). The trail left by a boat is literally reflected on this obstacle. Students can check with this tool the laws of reflection: the angle of incidence of the waves is congruent angle of reflection! The picture on the left you can see the 'interference between the wavefronts of two trails, photographed on 6/11/2006 always along the Thames (the exact coordinates are 51 ° 27' 40.79'' N, 0 ° 16 '05.69 '' E). Recall that, if the water is very low, ie, when the depth h is smaller than the wavelength λ, the speed of the waves in the water can be obtained by extracting the square root of the product between the depth h and the acceleration of gravity g. What we see here photographed by satellite the 28/04/2002 at Villaricos in Andalusia (coordinates 37 ° 14 '04:59'' N, 1 ° 47' 04.79'' E) is the phenomenon of refraction: if the waves reach an area where the water is low, the friction with the bottom of the slow ago, their wavelength decreases and they change the direction of propagation. In short, whatever the angle at which the waves approach the shore, they tend to refract and to arrive always parallel to it! Another extraordinary example of refraction of the waves, this time taken in Sardinia on 18/8/2010 (coordinates 39 ° 46 '12.64'' N, 8 ° 27' 28.82'' E). The instrument "ruler" Google Earth allows to measure the distance between two geographical points; thanks to it students can measure the wavelength and calculate the speed of the waves, in which deep water is approximately equal to the square root of the length d 'wave for the acceleration of gravity divided by two pi greek. If λ = 100 m, v = 12.5 m / s. Here we are in Chichiriviche, Venezuela, in April 2006 (coordinates 10 ° 55 '29.88'' N, 68 ° 15' 26.93 W). Even in this case, the approach of the waves at lower backdrops ago tilt variously their wavefronts. Here it is also possible to observe together the phenomena of refraction, reflection on the coasts and cliffs and 'interference between direct waves and those reflected! This photograph introduces us to 'sound here is two tuning forks with its hammer and a cane sores. The tuning fork (from the greek "for half of all", ie agreement obtained by means of all frequencies) vibrate on a fixed note (770 Hz) and are therefore used to tune musical instruments, also the arrangement in figure allows to study the resonance phenomenon (hitting the one, begins to vibrate the other). instead the barrel allows sores, blowing nell'ancia, to issue notes of different height varying the length of the cannula. A really fun experience! The image in the figure depicts an electromagnetic tuning fork. It is a tool similar to that shown above, however, unlike that, is formed by an electromagnet and by a tuning fork, which are part of the same circuit. Closing the circuit with a battery, the electromagnet attracts one of the prongs, thus opening the circuit. But in this way the circuit is opened, the electromagnet is deactivated, the tine returns to the initial position closing the circuit and making attract again by the electromagnet and so on, ensuring that the sound will continue until the power supply continues. This experience is strongly recommended whenever discusses the phenomena in wavy children in elementary and secondary schools. Basically you take a tuning fork, leans against a sheet of paper on his sounding board and there you have the iron filings. So you strike the tuning fork, and you will see the iron filings "dance" on the sheet of paper, raised by the vibrations to which the resonance is subject (a colleague of mine has even used the metaphor of the filing that "fries"). Surely a simple way to explain the concept of wave, here comes a short digital movie that illustrates the experience. What you see in this photograph is the device used to prove the 'existence of standing waves. What are they? Striking an object causes a motion that, if there were no friction, it would be harmonious, and every point, swinging, induces its neighbors to do the same, creating a wave that propagates along the rope to one of two extremes fixed, where it reflects generating a second wave that propagates in the opposite direction. The motion of a point of the object is therefore the result of the superposition of two waves: a progressive and a regressive. Their overlap gives rise to a wave in which all the points are either in phase or in phase opposition, the wave does not propagate more and is called stationary. The points of the stationary wave which do not fluctuate ever, having amplitude of oscillation constantly equal to zero, say they are nodes of the wave. To view is a square of dark metal foil on which it is distributed in the fine sand (see photo above). If hitting a corner of the foil, it is observed as the grains of sand tend to thicken along a cross which divides the foil into four equal parts, and this because the standing wave has a wavelength equal to the side of the lamina, and consequently nodes are exactly the middle of it! If instead of hitting the center of one side, it produces a stationary wave different, in which the nodes coincide with the points of the diagonals of the lamina. It should be noted that, by continuing to strike the foil, the grains of sand were out by diagonals continue to oscillate up and down, while those in the diagonals (nodes) do not move: QED! Espeerienza this is also a short digital movie . Another classic experience, highly effective at primary school: the bell under the vacuum bell. In practice, inside the vacuum bell is mounted a bell put in action thanks to the electric cables visible in the figure. You activate it, so that students may hear clearly the clink, then one begins to draw air from beneath the bell through the vacuum pump (see mechanics ) As the air comes out, you realize that the sound of the bell is no longer audible, because it fails the air that carries the sound waves. Simple, is not it? The one shown in the figure is a mobile rudimentary that everyone can build. Just take two plastic cups (in this case two cups of yogurt) and connect them with a long wire set into the bottom washing shorts by a node. As shown by two students photographed, if they are off by several meters and a whisper in his glass, the other will feel all putting your ear, because the sound waves propagate much better in a solid medium (the cord) that is not in the air! The instrument is normally called visible here stethoscope (from the greek "observation of the chest, " though more properly it should call stetofonendo, that is "listening to the chest"), and was created in its current form in 1851 by Arthur binaural leared.Since ( 1822-1879). The principle is the same as the previous phone, a disc structure receives heartbeats, which are transmitted and amplified by a canal that divides and reaches the ears of the doctor. Tool truly historic, today has been mostly replaced by electronic instruments of great precision. This pan flute (named after the greek god who would have invented it) is not just to blow rustic melodies, but to bring out the background noise. In fact we are all immersed in a low background noise, and putting your ear to the various reeds gradually we hear different tones of it, because of their length and thus their different resonance. This is also the reason why, putting your ear to a seashell, seem to hear in it the sound of the sea: the whole effect of the background noise! An acoustic instrument really interesting is the Quincke tube reproduced here. The sound picked up by the trumpet, is divided into two tubes and met again at the ear on the opposite side. Stretching one of the two branches as you do with a trombone changes the length of the two paths and are experiencing impressive acoustic interference with the sound that fades to certain lengths and strengthened for others. And here's a metronome (from the greek Metron, measure and nomos, rule), an instrument very familiar to musicians, because it serves to indicate the detachment of the time in music and keep time during performances; it is formed by a double pendulum, put moving from an adjustable mechanism clockwork. Normally it is believed that it was patented in Paris by a certain Johann Nepomuk Maelzel of Regensburg, which is indispensable in every lesson in musical acoustics. This is a monocordo, usable for experiments relating to 'height of the sound. It has a rope swinging, which emits a sound wave as a function of the voltage and length. The mobile bridge can be moved, and this allows to vary the height of the notes issued from high to low. Another museum piece: a cash distribution for reeds sound. In practice, the connecting to a turbofan and it provides air to the metal pipes, each of which emits notes of different frequency in relation to the length, the thickness, material, etc. (exactly as different strings, if plucked, emit notes of height different). If the monochord is the ideal prototype of stringed instruments, this feeds all the prototypes of wind instruments. And here's a real wind instrument, and that instrument! This is the 'organ of the sanctuary of Santa Maria in Brunello (VA), whose rector is my friend and has allowed me to publish this photo. The organ is, as they say, a "tool aerofono keyboard", the piano is a keyboard, but it is a percussion instrument because the buttons operate the hammers that hit the strings. Instead the compressed air generated in the organ bellows is sent through the reeds, brass and their intensity is precisely adjusted by means of buttons. According to tradition, the organ was invented by the greek Ctesibus who created a hydraulic organ, that is powered by water. After a wind instrument, here is a percussion instrument: it is the battery with which several students have performed during the festival at the end of the school year 10/6/2006. The name means "large quantities" of artillery pieces, coming from military language, but it came to indicate both the most complex of batteries ( battery power ) and the most complex of drums, cymbals and other percussion instruments we can see in the picture . Congratulations to the player! A piece that can not miss in this Virtual Laboratory is the phonograph, the ancestor of our CD players. Invented by Thomas Alva Edison in 1877, consists of a pin that reads a vinyl record (some are visible on the right), which transmits the groove pin a wave motion then converted into sound waves by an electromagnetic device. Vinyl disks 33 and 45 rpm are still sought after by collectors. A delightful experience can be achieved with this frequency generator connected to a speaker: acting appropriately on the monopole is possible to output to the amplifier across the spectrum of frequencies by infrasound to ultasuoni, and so ensure that the human hearing range is between 16 to about 16, 000 Hz! The strange trumpet shown in the figure is a microwave emitter. Microwaves are electromagnetic waves whose wavelength is between a millimeter and a meter, which is why they are distinguished, depending on the wavelength, in the millimeter wave, centimeter and decimetre. They are usually used in radio communications and to transmit multiple telephone and television signals. The microwaves are perfect for many educationally interesting experiments such as verification of their interference, diffraction and polarization (see immediately below). The strange object in the figure, seen from the front and cut for a better visualization, is a lens of paraffin. Yes, you read right: a lens like that of our glasses, as evidenced especially the view of cutting, used to show the refraction of microwaves, as well as to demonstrate that they undergo the same identical effects obvious from light waves that pass through the common lens glass. Only, its size and its focal length are much greater than those of the glasses, because the wavelength of microwaves is greater than the wavelength of light! The diameter is about 30 cm. This looks like the cover of a manhole, but it's a very important educationally device: a grid of polarization for microwave. If the stands between an emitter and a receiver of microwaves so that the bars are parallel to their direction of polarization, the waves pass entirely; if it rotates 90 °, does not pass absolutely nothing, demonstrating that microwaves are polarized, ie they have a preferred direction of oscillation! Here we see a power supply for klystron. For those who had never heard this strange word, derived from the greek klyster (syringe) and English electron (electron), I will say that it is an electron tube used to generate high-frequency oscillations, corresponding to centimeter or decimetre waves, and then microwave. The klystron is therefore mainly used in radar transmitters and receivers. This photograph really extraordinary, taken by Ensign John Gay of the U.S. Navy, is a supersonic, namely an F/A-18 Hornet, when it breaks down the wall of sound. The sound waves emitted from it will flatten forward because of 'Doppler effect and produce a layer that the plane must destroy to exceed Mach 1. The violent decompression causes the condensation of water vapor in the bubble visible here! Let's go back to Google Earth to illustrate the phenomenon of 'wave cone. Consider the wake left by this boat in the River Thames at London on 6/11/2006 (coordinates 51 ° 28 '05:40'' N, 0 ° 15' 12.18'' E). If a body is moving in a medium at a higher speed of sound in that medium, the spherical sound waves "left behind" and give rise to a wave of this type, in the shape of a cone. The "Bang" supersonic is constituted precisely by this wave! With this we leave the acoustic and enter the domain of ' optics . This science was started by Isaac Newton with his fundamental work "Optiks". Galileo Galilei before him had attempted the measurement of the speed of light by a lantern to discover one of his disciples sent on a hill far away, but the distance was too short, and you only measured the reaction time of the assistant's arm. The speed of light was measured for the first time by Ole Roemer in 1675. The beautiful photograph in the figure illustrates in the best way possible the formation of light rays, and then the rectilinear propagation of light. The sun peeps out from behind a cloud and in fact produces a fantastic arabesque in the sky. Newton, with his corpuscular model, explained the rectilinear propagation through the principle of inertia applied to the corpuscles of which would be light; Huygens instead, with its corpuscular model, explained arguing that the wave propagates in a uniform medium so that the rays (lines perpendicular to wave fronts) results straights. Another experience that is easy to carry in any environment (here in the kitchen of my house on 6/1/2005): one called the "broken stick". Just slide in a glass of water, a spoon, and it will appear as if it was broken in two. A joke cause this is the phenomenon of refraction of light in the transition from air to water. Looking at the glass from above, the phenomenon is even more obvious! An experience that I was shown at primary school ... The objects are divided into opaque (no light passes through them), transparent (light passes through them easily) and translucent. These latter are traversed by the light, but through them we can distinguish only the greater or lesser brightness, not the shapes of objects. This is the case of the glass panes in the window wells of this winery. In this photo you can see portraits of two shelves of our Virtual Cabinet, on which are placed in plain sight some spherical mirrors for optics experiments. With them, you can check the construction of the image generated by a spherical mirror of small curvature depending on the laws of geometrical optics, a subject sadly neglected in today's Physics lessons, and instead I judge educationally very useful to show the close connection between geometry theoretical and observational physics. This photograph shows an easy experience, useful to illustrate to children the phenomenon of reflection of light. Just open a CD box at a right angle so that the transparent facade is in front of a burning candle. Interposing a glass between the candle and our eyes we can see the flame burning inside the glass. Indeed, the image that you see in the container comes from both the candle from the light reflected from the glass; doing superimpose the two images, the brain perceives them as if they came from a single source, the one you see in the glass! With the darkroom you can perform many spectacular experiments, including the 'observation of an eclipse of the sun. As is known, fix this rare and magnificent astronomical phenomenon can cause serious permanent damage to the eye, but during the partial eclipse of the sun on 29 March 2006, it was enough to project the image of the sun on the bottom of the darkroom to see clearly his record reduced to a crescent-shaped, as shown in the box!

Source: www.fmboschetto.it

ACCO Brands Apollo Write-On Transparency Film, 8.5 x 11 Inches, Clear, 100 Sheets per Box (VWO100C-BE)
Office Product (ACCO Brands)
  • Write-on transparency sheets
  • For use with transparency marking pens
  • Not for use in any printer or copier
  • Great for last-minute visuals and working examples
  • Box of 100 clear sheets

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Hahahaha...did you call me a cheap bastard

On line for everyone to see?...i cant deny it...i am indeed a cheap bastard...in true uri fashion i started with the cheapest projector returning each one till i reached the $200 range...the miror driven photo projectors suck...ultimately i found the overhead projectors we used in school to provide the best results but you have to use transparent transfer paper or plastic sheets requiring time to trace imagery...after trial error trial error i realized i was just crippling myself with a technological mirage once again...dont let technology make you stupid...just fuckin draw like an artist.

Scenes at sea, through many eyes  — Durham Herald Sun
Jenny Morgan's “Intimations of Life at Sea” contains poems inspired from interviews, printed on crumpled sheets of paper that hang from the gallery.

National CineMedia, Inc. (NCMI): National CineMedia Management Discusses ..  — Seeking Alpha
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3M Commercial Ofc Sup Div 3M AF4300 Write-On Overhead Projector Transparency Film, Letter Size, Clear (Box of 100)
Kitchen (3M Commercial Ofc Sup Div)
  • Write or draw directly on film using transparency or china markers
  • Ideal for last-minute visuals
  • Create and present crisp charts and graphs
  • Not for use in printers or copiers
  • Clear; Width: 8 1/2 ; Height: 11
Expo Vis-A-Vis Wet Erase Markers, 8 Colored Markers (16078)
Office Product (0)
  • Wet Erase markers for overhead projector transparencies and all other types of films, acetates, and laminated calendars
  • Won t fade or bubble under intense heat
  • Durable fine point tip produces thinner, detailed lines
  • Erases with a damp cloth
  • 8 Pack of Markers includes 1 each of Black, Blue, Green, Yellow, Orange, Red, Purple and Brown
Dry-Lam Dry-Lam Overhead Projector Accessories - Write-On Film, 100 Sheets
Art and Craft Supply (Dry-Lam)
School Smart School Smart Medium Weight Write-On Transparency Film - 8 1/2 x 11 - Pack of 100
Office Product (School Smart)
  • Sold as a Box of 100 sheets
  • Can be written on, wiped clean and reused multiple times
  • Compatible with most dry and wet erase markers
  • Great for stacking multiple graphs to show changes over time
  • Ideal for last minute slides and presentations

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  • Avatar Jasmine Where can I find colored sheets used on overhead projectors?
    Feb 17, 2010 by Jasmine | Posted in Engineering

    I don't know want to use them on overhead projectors. I need it to change the color …lue.

    I know there's a Michaels and AC Moore where I live. There's Office Depot and Staples, as well. Help?

    oh they're like thin plastic sheets.
    are you sure they have them?

    • Ya

      Office depot and Staples
      and there is this store called The Teacher Store or whatever. that's were the teachers get there class room stuff at

  • Avatar Hikari What type of projector is this?
    May 09, 2011 by Hikari | Posted in Other - Electronics

    My university has it to use for some professors. It looks like a white version of an overhead projector. But, instead of clear transparency sheets and such, a professor writes on a sheet of paper and the projector-projec …a that shows up on a LCD screen electronically. Nothing actually 'projects' with light. It's like if you hooked up a laptop to a presentation screen to view a powerpoint.

    What's the name of this contraption?

    • It is called a document camera. Elmo is the major brand name. It is pretty simple - on the top of the neck is a color video camera pointed down at the base. The camera outputs video to the projector.