A washing up bowl holds about 10mm depth of water. A control varies the frequency of an audio generator driving a loudspeaker underneath the bowl, causing patterns of wavelets in the water. Some lovely standing wave patterns can be produced, and at some intermediate frequency, the amplitude of the waves increases to cause "splashes" about 100 to 200 mm high. One of our best exhibits for the visually impaired, the sides of the exhibit also transmit the sound vibrations, which can be felt.
This exhibit, about 2m in length, consists of several dozen "magic wand" sticks spaced about 50 mm apart, joined together by a length of elastic. The end sticks may be moved up and down, and their motion is transmitted to the next elements in the chain, so that a wave motion may be seen to propagate along the exhibit. This exhibit can be used to demonstrate a wide variety of wave motion features, such as low frequency propagation / high frequency cut off, attenuation (decay) of amplitude, and the inverse relationship between frequency and wavelength.
Meteosat Weather Pictures
The user can use a trackball to select from 10 different views of the planet, and can additionally choose from infra-red, water vapour or visible light sensors. All the views appear as "movies", showing how the weather patterns have moved over the past day or so.
Just what it says, a red laser light is projected onto a white surface within the exhibit. The user uses two controls to adjust the pattern produced.
Possibly the most favourite exhibit in Discovery. The user stands close to the light green wall and presses a button, which causes a "security" type floodlight to illuminate for about a second, after which the user's shadow is seen to be left behind on the wall, even when the user has stepped back to see it! The wall is painted with fluorescent paint, which glows for a few seconds when it has been illuminated. The shadow shows where the light did not reach the wall.
This well known exhibit is simply a garden water barrel with a hole in one end. When the user hits the rubber closed end, a puff of air is projected from the open end and travels across the room, eventually hitting a curtain “target” about a second later. The delay is surpsising, as is the force of the air if you stand in front of the curtain and become the target yourself.
Face to Face
An immensely popular exhibit, two people sit opposite each other, either side of a half-silvered mirror. By adjusting the light levels on either side of the mirror, and working cooperatively, they can each adjust the image seen in the mirror from 100% their own reflection, through to 100% of their friend's face, via mixtures of the two. There are some weird images to be seen - people wearing each other's glasses, or wives with their husband's beards. In some cases, we have seen two parents mix up their faces to get images of their children!
Bubble Sort Train Set
An attractive exhibit showing in a mechanical way how the mathematical "Bubble Sort" works. The exhibit consists of a computer-driven 00 gauge electric train having three trucks. The user enters a desired order for the trucks, say, 1-3-2 or 2-3-1, and the system then automatically arranges the trucks in that order by swapping pairs of trucks using the siding.
Intelligent Robot Arm
This high-tech exhibit is designed to question one’s assumptions concerning intelligence, and to raise queries about system design and sensing. The user instructs the robot arm via a touch screen, requesting a particular arrangement of the coloured blocks. The arm will move the blocks around to achieve the desired result, without delaying itself by obstructing blocks it will require later on in the arrangement.
An acrylic-topped box holding polystrene beads and other objects. When the surface is rubbed with a variety of cloths (or just one's hand), the pieces of polystyrene move around quite vigorously. This exhibit works best in dry weather.
A window approximately 500 mm square reveals an apparent plasma sphere, many coloured and ever-changing, apparently about 1.5 metres in diameter. The spherical illusion is generated by four mirrors placed in front of a television screen, in a similar manner to a kaleidoscope. the overall effect is arresting.
A great favourite with our younger visitors, a horizontal window about 700 mm diameter shows what is apparently a bottomless brick-walled well. The exhibit illumination is turned on by using a switch. The well is really only about 400 mm deep, and has a mirror at its lower end, and a half-silvered mirror at its top.
This is a fun demonstration of one of the most basic properties of an ellipse. Using a ramp as a sighting aid, a marble is made to travel over a black dot, placed at one focus of the elliptical table. The marble will bounce off the cushioned edge of the ellipse and will always ring the bell, which is placed at the second focus.