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03:18 Bundesanstalt für Wasserbau (BAW) German 2010

Elbemodell Hamburger Yachthafen

Big container ships pass the marina of Hamburg, situated close to Wedel at the lower River Elbe, and affect the moored yachts with their bow and tail waves. A scale model of the River Elbe and the Hamburg marina was built up in the Hamburg office of the BAW. Water level, wave height and wave propagation during individual trips and encounters are measured in three dimensions and are analysed. A line jetty in front of the harbour entrance is a possible structural modification - as precise measuring methods showed - used in addition to a reduction of the ships' speed.
  • Published: 2010
  • Publisher: Bundesanstalt für Wasserbau (BAW)
  • Language: German
05:26 IWF (Göttingen) German 2003

Trägheit des Magnetfeldes: Induktive Schaltverzögerung

The switching on and off of electric devices is usually characterized by their instantaneous response. The presence of inductors with large self-inductance can, however, cause considerable delays. Iron cores can lead to additional delays resulting from a change of the magnetization. Such delays, extending over minutes, will be shown here. A large copper spool is wound on a heavy closed iron core. It can be connected with a switch to a 2 volt accumulator (lead-acid battery) and a projection ammeter of short response time (less than 1 sec). The time is measured with a large, hand-operated (historic) stopwatch. These experiments always are extremely surprising, considering that we tend to associate electric phenomena with the idea of the instantaneous, the timeless.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
01:21 IWF (Göttingen) German 2003

Bestimmung des elektrischen Erdfeldes

The electric field of the earth will be determined. A parallel plate capacitor of area 1 m2 is attached to the end of a long bamboo pole. The capacitor is connected to a ballistic galvanometer calibrated to measure current pulses (charges). On a balcony outside the lecture hall, the capacitor is held with its plates horizontal.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
02:09 IWF (Göttingen) German 2004

Kapazität einer Kugel

Experimental determination of the capacitance of a sphere.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
07:36 IWF (Göttingen) German 2004

Stromlinien-Modellversuche

The goal is the demonstration of two-dimensional streamline patterns as they occur when non-viscous fluids flow around obstacles. The patterns shown are models, since they have been produced in a viscous fluid under conditions of laminar flow.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:59 IWF (Göttingen) German 2004

Maxwellsche Scheibe

A body that is being accelerated downward weighs less than when at rest. This is demonstrated with a flywheel on a shaft suspended on one arm of a household scale (Maxwell's disk). It is suspended on one arm of the scale with two strings which wrap around the thin shaft. When the flywheel is released, it accelerates downward, and the scale reads a reduced weight. During the subsequent rise (the flywheel still accelerating downward!) the scale again indicates a reduced weight.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
00:54 IWF (Göttingen) German 2004

Schwanke Achse

An object rotates stably around its axis of maximum moment of inertia, even if it is attached to a bent supple shaft. The experiment also shows that particles leave a rotating object by flying off in a tangential direction.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:27 IWF (Göttingen) German 2004

Elektrischer Wind

At sharp corners, even small voltages can lead to large electric fields. They can ionize the surrounding air, making it electrically conducting.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:22 IWF (Göttingen) German 2003

Zirkulare Schwingungen

Through superposition of the linear oscillations of two leaf springs of almost equal frequencies, linear, elliptic and circular oscillations can be generated and shown by optical projection.
  • Published: 2003
  • Publisher: IWF (Göttingen)
  • Language: German
02:42 IWF (Göttingen) German 2004

Wirbelstrombremse

Forces are demonstrated which arise when an electric conductor moves through an inhomogeneous magnetic field.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
00:50 IWF (Göttingen) German 2004

Kräfte im elektrischen Feld

Between two surfaces separated only by a small gap, small voltages can lead to appreciable forces.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:22 IWF (Göttingen) German 2004

Seifenblasen im elektrischen Feld

The repulsive force between two bodies carrying charges of the same sign will be demonstrated.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
03:28 IWF (Göttingen) German 2004

Magnetischer Spannungsmesser

A long induction coil wound on a flexible hose is used to explore the magnetic field near current carrying conductors and also near a permanent magnet.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
03:10 IWF (Göttingen) German 2004

Induktion in bewegten Leitern

A conductor moving in a magnetic field experiences an electric field.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
03:04 IWF (Göttingen) German 2004

Induktion in ruhenden Leitern

A changing magnetic field generates an electric field.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:55 IWF (Göttingen) German 2004

Magnetisches Drehfeld

A rotating magnetic field results from the superposition of two magnetic fields oriented perpendicularly to each other, which vary sinusoidally with equal frequency, but with a phase difference, ideally of 90 degrees.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
02:28 IWF (Göttingen) German 2004

Elektromagnet

It will be shown that in a small electromagnet surprisingly large forces can be generated. However, these forces decrease drastically with the introduction of only a small gap between the pole faces.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:21 IWF (Göttingen) German 2004

Sphärische Aberration

The imaging error called "spherical aberration" is demonstrated by imaging a small coil of a light bulb.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:03 IWF (Göttingen) German 2004

Paramagnetische Materie

Paramagnetic matter gets pulled into regions of a large magnetic field. For the demonstration, liquid oxygen is poured into a shallow container placed in front of an electromagnet with non-parallel faces.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:33 IWF (Göttingen) German 2004

Induktionsläufer

Eddy currents induced in an aluminum disk in a moving inhomogeneous field tend to move the disk along with the field. This is the principle of the induction motor.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:48 IWF (Göttingen) German 2004

Reflexionskegel

The reflection of light is demonstrated using a polished steel tube. The reflected light has the shape of a cone.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
12:25 IWF (Göttingen) English 1999

Pilobolus, a specialised coprophilous Fungus

Pilobolus, the hat thrower, is a minute fungus belonging to the Mucorales, which grows on the dung of herbivores. It has adapted itself to their way of life and ingestive habits: in the daily rhythm of its phototropic sporangiophore development, violent sporangium discharge, the attachment mechanism of its sporangia to herbage, and spore germination. The video-tape carefully documents the asexual development of the fungus by time lapse cinematography and lays emphasis on the phototropism of the sporangiophores and discharge of the sporangia.
  • Published: 1999
  • Publisher: IWF (Göttingen)
  • Language: English
06:45 IWF (Göttingen) German 1988

Partikelbewegung und Zerkleinerungsvorgänge in einer Turbomühle

In order to detect possibilities of improving the design of mills and the energy utilization, the stresses to which the particles were exposed in the individual areas of a turbo-mill were recorded and analsed with the aid of high-speed cinematography. The tests with white pepper were executed at a rotor circumferential speed of u=40 m/sec., with a material throughout of M[M]=150 kg/h and with varying configurations of the peripheral grid. The tests covered the percentage of material comminuted by the first impact, the penetration into and the discharge from the baffle plates of the rotor, the conditions prevailing in the rotating material circle between rotor and peripheral grid, as well as the the passing of the particles through the peripheral grid.
  • Published: 1988
  • Publisher: IWF (Göttingen)
  • Language: German
13:56 IWF (Göttingen) German 1997

Stridulationsverhalten der Feldheuschrecke Omocestus viridulus

Omocestus viridulus, der Bunte Grashüpfer, ist ein typischer Vertreter der Feldheuschrecken der Unterfamilie Gomphocerinae mit gut entwickeltem akustischen Kommunikationsverhalten. Der Lautapparat besteht aus einer Reihe auf Resilinbasen gelenkig eingesetzter Zäpfchen an der Innenseite der Hinterschenkel, die über die vorstehende Radialader der Vorderflügel gestrichen werden. Der Film zeigt den Stridulationsapparat von Omocestus viridulus und die verschiedenen situationsbedingten Lautäußerungen im natürlichen Habitat, z. T. in 16facher Tonzeitdehnung.
  • Published: 1997
  • Publisher: IWF (Göttingen)
  • Language: German
10:19 IWF (Göttingen) English 1982

Gestalt Perception in the Common Toad - 2. Modification of Prey Recognition by Learning

Self-conditioning of the common toad to prey smell and modification of the innate releasing mechanism for prey capture behaviour. "Hand-conditioning". Fine differentiation of prey dummies by stimulus-specific habituation.
  • Published: 1982
  • Publisher: IWF (Göttingen)
  • Language: English
13:56 IWF (Göttingen) English 1997

Stridulatory Behaviour of the Acridid Grasshopper Omocestus viridulus

Acoustic communication is well developed in acridid grasshoppers. Especially species of the subfamily Gomphocerinae display elaborate stridulatory behaviour. Their stridulatory apparatus consists of a row of cuticular pegs at the inside of each hindleg and an enhanced vein of the elytra. Species specific acoustic signals are produced by rhythmically rubbing the hindlegs against the elytra. The video demonstrates the stridulatory apparatus of Omocestus viridulus L. (Saltatoria, Acrididae) and shows the different leg movements and song types of the animals in their natural habitat.
  • Published: 1997
  • Publisher: IWF (Göttingen)
  • Language: English
10:17 IWF (Göttingen) German 1982

Gestaltwahrnehmung bei der Erdkröte - 2. Modifikation des Beuteerkennens durch Lernen

Selbstdressur der Erdkröten auf Beuteduft und Modifikation des AAM für das Beutefangverhalten. Handdressur. Feinunterscheidung von Beuteattrappen durch reizspezifische Gewöhnung (s. a. Film C 1805).
  • Published: 1982
  • Publisher: IWF (Göttingen)
  • Language: German
16:22 IWF (Göttingen) German 1982

Gestaltwahrnehmung bei der Erdkröte - 1. Angeborenes Beuteerkennen

Prey-catching behaviour. Analysis of the visual-key-stimulus "prey" through experiments with dummies. ("worm/antiworm" configuration). Behaviour with changing stimulation-background contrast. Direction, speed and contrast variance in shape recognition.
  • Published: 1982
  • Publisher: IWF (Göttingen)
  • Language: German
19:29 IWF (Göttingen) German 1982

Gestaltwahrnehmung bei der Erdkröte - 3. Neuroethologische Analyse des angeborenen Beuteerkennens

Neuroethological investigational methods. Configurational prey recognition and its directional variance. Neurophysiological recording experiments show the activities of individual neurons in the optic tectum and caudal dorsal thalamus. Triggering of prey capture and fleeing by specific point stimulation of the brain. Modification of the innate releasing mechanism through local brain lesion. Animated demonstration of the toad brain and a model of the innate releasing mechanism.
  • Published: 1982
  • Publisher: IWF (Göttingen)
  • Language: German
19:25 IWF (Göttingen) English 1982

Gestalt Perception in the Common Toad - 3. Neuroethological Analysis of Prey Recognition

Neuroethological investigational methods. Configurational prey recognition and its directional variance. Neurophysiological recording experiments show the activities of individual neurons in the optic tectum and caudal dorsal thalamus. Triggering of prey capture and fleeing by specific point stimulation of the brain. Modification of the innate releasing mechanism through local brain lesion. Animated demonstration of the toad brain and a model of the innate releasing mechanism.
  • Published: 1982
  • Publisher: IWF (Göttingen)
  • Language: English
00:48 IWF (Göttingen) German 2004

Perspektive

Two-dimensional images of three-dimensional structures have a perspective, that is a certain ratio of size and distance for things which lie behind each other. The perspective depends on the position of the centers of the projection, which in imaging lie in the centers of the entrance- and exit-pupils. Using the images of two objects positioned at different distances from the imaging lens, the perspective and its changes will be shown.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:45 IWF (Göttingen) German 2004

Chromatische Aberration

Chromatic aberration occurs in imaging as result of the wavelength dependence of the index of refraction. It will be demonstrated on a special example.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
02:31 IWF (Göttingen) German 2004

Auflösungsvermögen

It is shown that in an optical image the individual light spots are diffraction patterns caused by the opening of the imaging lens. The resulting limit of the angular resolution is demonstrated with the aid of two pairs of holes with different separations.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
02:46 IWF (Göttingen) German 2004

Polarisiertes Licht

The plane of polarization of a light beam which has been polarized by passing it through a Nicol prism is made visible through scattering in a slightly milky liquid.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:16 IWF (Göttingen) German 2004

Krummer Lichtstrahl

A trough contains a sugar solution with a vertical concentration gradient, so that its index of refraction decreases with increasing height. A laser light beam enters the trough, tilted slightly against the horizontal direction. As it moves through the liquid, it is bent, as can be observed through scattering.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
01:58 IWF (Göttingen) German 2004

Astigmatismus

The imaging error called astigmatism occurs when light travels not parallel to the axis of the lens, but under an angle. Instead of image points, extended lines or streaks are formed.
  • Published: 2004
  • Publisher: IWF (Göttingen)
  • Language: German
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