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Difracción del sonido

Figura:
La difracción es una característica típica de las ondas sonoras cuando éstas encuentran un obstáculo.

La difracción de las ondas sonoras es un mecanismo físico que asegura la entrada de éstas en sombras acústicas.
Eso significa que el sonido es audible en áreas que están separadas de la incidencia directa del sonido, tal como detrás de obstáculos.

Información e ideas:
Se puede demostrar la difracción de la luz cuando un haz de rayos paralelos de luz monocromática se dirige a una abertura pequeña. Una pantalla colocada detrás de la abertura da una figura de difracción (franjas brillantes y oscuras que pierden intensidad mientras más alejadas están). Con el sonido, una referencia directa al mundo diario de los estudiantes es aún más fácil: ¿por qué pueden oír ruido de una calle frente a un edificio aun cuando ustedes están detrás del edificio?
Hay disponible mayor información sobre este gráfico, como hoja informativa, en el portal de medios didácticos de la Siemens Stiftung.

Pertinente a la enseñanza de:
Sonido/acústica: parámetros
Vibraciones y ondas

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El piano: un cuerpo resonante

Fotografía:
El piano de cola y el piano constituyen buenos ejemplos del gran significado de las cajas de resonancia con respecto al volumen y al sonido.

El bastidor y el aire en el piano vibran en resonancia con la cuerda que se acaba de tocar. Mientras que el piano de cola moderno "llena? salas de concierto en su totalidad, su predecesor histórico, la espineta, ofrece sonoridad apenas para la sala del hogar. Además del volumen, el matiz del tono de la espineta es también menos profundo. Esta comparación clarifica la importancia de la caja de resonancia, tanto en la producción de sonido en general, así como también en la música en particular.

Información e ideas:
Un ejemplo práctico del campo musical muestra cuán importantes son los campos de la física y la acústica para el mundo del arte y las comunicaciones.

Pertinente para la enseñanza de:
Sonido/acústica: parámetros
Vibraciones y ondas

Medientypen

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Lernalter

6-18

Schlüsselwörter

Sonido

Sprachen

Spanisch

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Siemens Stiftung

Vom Wasserrad zur Turbine (GS)

Fotocollage:
Fotos von einem Wasserrad sowie drei verschiedenen Turbinenarten.

Schon früh setzte man Wasserräder ein, um die Energie von Wasser zu nutzen, z. B. zum Antreiben eines Mühlrads. Die Turbinen, die in Wasserkraftwerken eingesetzt werden, sind eine Weiterentwicklung des klassischen Wasserrads, um Generatoren für die Stromerzeugung anzutreiben. Diese Turbinen heißen nach ihren Erfindern: Pelton, Kaplan und Francis.

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Speicherkraftwerk

Grafik:
Funktionsprinzip eines Speicherkraftwerks.

Beim Speicherkraftwerk wird von Natur aus nachfließendes Wasser mithilfe eines Stausees angestaut und für Bedarfsspitzen bevorratet. Das gestaute Wasser wird dann mittels Druckrohrleitungen zu den Turbinen des niedriger gelegenen Kraftwerks geführt. Die gesamte Lageenergie des Wassers im Speicherbecken ist also ein Energiespeicher für Spitzenzeiten. Kleinere Speicherkraftwerke verwenden Pelton-Turbinen, große Speicherkraftwerke (großer Druck und große Wassermenge) verwenden Francis-Turbinen.

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The Ear, Hearing and Hearing Impairment: Speech as highly complex sound signal

Graphic:
Oscillographic curve of the spoken sentence "It's raining cats and dogs".

Speech sounds are fluctuating sound signals where the composition of frequencies changes all the time.
Aperiodical overlap periodical parts. Unlike noises, some of which have similar frequency curves, sound in speech is always the carrier of meaning or of messages sent out by the speaker. Other noises like smacking of lips, hissing, rhythms, basic pitch are typical of the individual (acoustic fingerprint) but not essential for the speech content!

Information and ideas:
Supplementary to worksheets and transparencies.

Relevant for teaching:
Sound/acoustics: parameters
Vibrations and waves
Communication and understanding

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Lens and imaging equation

Schematic diagram:
The light rays emanating from the object must be collected through a lens to form the points of an image. The imaging equation describes the applicable laws.

At least two of the following rays are needed to construct the image:
· Ray from the object parallel to the optical axis (parallel ray)
· Ray from the object through the focal point of the lens (focal ray)
· Ray from the object through the central point of the lens (central point ray).

The central point ray passes through the lens without changing direction. The parallel ray passes through the focal point on the other side of the lens, and the focal ray becomes the parallel ray.

Note: The imaging equation is also frequently known as the "lens equation."

Information and ideas:
What are lenses needed for?

Medientypen

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Lernalter

13-18

Schlüsselwörter

Light Optics

Sprachen

Englisch

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Siemens Stiftung

Incandescent lamp

Photo:
The light in this incandescent lamp is generated by heating a filament to high temperatures.


In many light sources, for example, incandescent lamps or high-pressure gas-discharge lamps, a continuous light spectrum is generated by the interaction of large numbers of photons at very different energy levels. This means that the complete range of wavelengths is included, but in different proportions depending on the temperature.
Incidentally, the wavelength and energy distribution of incandescent lamps fit the Planck radiation formula extremely well.

Information and ideas:
Example of how physical laws are translated into technical applications. Double-coiled filaments are used, among other reasons, to increase the radiant surface.

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Frequency differentiation in the uncurled cochlea

Labeled graphic:
High-pitched tones are heard in the front part of the cochlea, low tones are heard in the back part.

As the sense of hearing is able to differentiate locations of the nerves, it is able to recognize the frequencies.

Information and ideas:
This graphic is good for creating a link between the topics of "Sound? and "Hearing?.
Further information regarding this graphic is available as information sheet on the media portal of the Siemens Stiftung.

Relevant for teaching:
Perception of sound
Human hearing ability
Communication and understanding
The human body
Structure and functions of a sensory organ

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Excitation energy of a water molecule

Chart:
Water can absorb heat energy in the form of vibrations or movement of its molecules. This energy content depends on the physical state: steam contains more energy than liquid water, for example.

The material surrounding us takes on different physical states depending on pressure and temperature (in Kelvin): solid, liquid or gaseous. This also applies to water: During a phase change from solid to liquid and liquid to gas respectively the energy of the water molecules increases without the temperature rising - the diagram for water shows plateaus. The values of these plateaus are approx. 6 kJ/mol (melting heat) and approx. 40,7 kJ/mol (vaporization heat) respectively.

Information and ideas:
Ideally suited for explaining the topic of phase equilibrium.

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The Ear, Hearing and Hearing Impairment: Sound curve vs. frequency and amplitude

Chart:
Shows vibration with a high and loud tone.

With respect to the sound curve upper left, the lower left sound curve has twice the sound pressure (amplitude is twice as high). The upper right curve, however, has twice as high tone (twice the frequency). Bottom right, both the amplitude and frequency have been doubled.The following can be said about a sound curve:
- Amplitude stands for volume.
- The frequency indicates the pitch.

With high tones, the wave shapes are narrow and are repeated quickly, with low tones, the wave shapes are broader and are repeated more slowly.

Information and ideas:
Connection can be made to the curve discussion in Mathematics. To be used on worksheets, transparencies etc.

Relevant for teaching:
Sound/acoustics: parameters
Vibrations and waves

Medientypen

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Lernalter

11-18

Schlüsselwörter

Sound Wave (physics)

Sprachen

Englisch