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Siemens Stiftung

Phase diagram of water

Diagram:
A P-T diagram for pure water. The lines indicate the temperature and the pressure at which the solid, liquid, and vapor phases exist in equilibrium. All three phases exist in equilibrium only at the triple point; otherwise, there are a maximum of two phases.

In addition to the equilibrium curves (melting pressure curve, sublimation curve, vapor pressure curve), the diagram also includes the pressure and temperature data for the melting, boiling, triple, and critical points.
Attention: The axes of the diagram are not shown true to scale.

Information and ideas:
This diagram also reflects the density anomaly of water (lower density in the solid state than in the liquid state): The melting pressure curve shows a negative slope. The reason for the density anomaly is the hydrogen bonds.

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Siemens Stiftung

Speech signal - individual word

Chart:
Screenshot of the oscillographic curve of the spoken word "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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Siemens Stiftung

Speech recognition sentence - syllable - phoneme

Chart:
The components of speech, from phoneme to sentence presented visually.

The graphic shows the oscilloscope curve of the spoken sentence "It?s raining cats and dogs" and excerpts from the units from which speech is composed: sentence, word, phoneme.

Information and ideas:
Speech recognition and speech synthesis are very topical themes in the field of information and communication technology.
Further information on this graphic is available as information sheet on the media portal of the Siemens Stiftung.

Relevant for teaching:
The human body
Structure and function of a sense organ
Reception of impulses and information transmission
Sensory perception

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Siemens Stiftung

Thermal energy

Diagram:
Formulas for the thermal energy of gases and temperature as a function of their molar heat capacity at constant volume.

The thermal or internal energy of a substance is the sum of the kinetic energies of its atoms or molecules. This energy is measurable as temperature. If you supply heat to the substance, the particle speed increases and the temperature rises. In the case of molecular gases, the supply of heat in addition to the translatory motion can excite other forms of motion (rotation and oscillation). This finds expression in the stepped curve of the molar heat capacity (diagram at the right). The molar heat capacity of a substance is the amount of energy required to raise 1 mole of a substance by 1°C. For gaseous substances, the following applies: If the gas particles move only linearly (translation), the amount of heat that is required to raise the gas by 1°C remains constant at 3R/2. In the case of molecular gases, the molecules start to rotate when a specific temperature is reached. In this area (linear increase in the diagram), more energy must be supplied to raise the temperature by 1°C, since the energy goes not only into the translatory motion, but also into exciting the rotation. If all particles are made to rotate, the energy required to raise the temperature by 1°C is again constant at 5R/2. The rise at the point of transition from rotation to oscillation can be explained in a similar way.

Information and ideas:
The overview graphic summarizes the topic of thermal energy using the example of gases. You will find detailed explanations as well as an explanation of the heat in solid bodies in the guideline "What is energy?"

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Siemens Stiftung

Normal audiometric audibility limit

Chart:
Audiometric audibility limit of a person with normal hearing with typical frequency and loudness ranges for speech and music.

The speech range is that range of frequency and loudness where speech communication usually takes place. Within the audiometric audibility limit it is the kidney-shaped range. In our diagram it is coloured blue.

Information and ideas:
An attempt at comparing diagrams showing normal hearing and reduced hearing can be done by students individually - as homework. It is useful for testing written expression (English) as well as for testing basic skills from Mathematics or Physics (how to interpret a diagram, for example).

Relevant for teaching:
Hearing defects/hearing impairment
How hearing functions
Sound/acoustics

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Siemens Stiftung

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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Siemens Stiftung

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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Siemens Stiftung

Sound field and sound absorption

Schematic diagram:
Concentric propagation of sound waves. The lines of the same loudness are shown which decreases as the distance to the sound source increases.

Why do we hear less the further away we are from the source of sound?
Sound propagates from its source in a circular way, the sound energy spreads over an increasingly large area and the sound pressure decreases accordingly.
In a free sound field it decreases by about 6 dB every time the distance to source is doubled. Within a room, however, this only applies very close to the sound source.

Information and ideas:
Useful for discussing why we hear less the further away the sound source is.

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

Medientypen

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Lernalter

11-18

Schlüsselwörter

Chart Sound Wave (physics)

Sprachen

Englisch

Dieses Material ist Teil einer Sammlung

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Siemens Stiftung

Steam pressure curve and phase diagram of water

Charts:
The steam pressure curves (p-V diagram) and the phase diagram (p-T diagram) of water are compared.

If you heat water to 100 °C at normal atmospheric pressure, it turns into steam. But what effect does raising or lowering the pressure have on the vaporization temperature?
The answer to this is given by the steam pressure curve (T-curves in the p-V diagram on the left) and the phase diagram (p-T diagram of the right) of the water. Steam pressure is the term for the pressure at which gas and liquid are in equilibrium, i.e. the same number of molecules evaporate as condense back into water. Above the critical temperature (numerical values are given) the water is always gaseous, regardless at what temperature, and it can be treated as a real gas (Van der Waals equation, formula is given). At every temperature below the critical temperature there is a steam pressure for which there is a two-phase zone (liquid and gaseous). In the liquid phase range it is possible to recognize from the steep rise in the curves that liquid substances are barely compressible.
The critical temperature must not be confused with the triple point temperature (see p-T diagram). This characterizes the values of temperature and pressure at which all phases (solid, liquid and gaseous) are present simultaneously.

Information and ideas:
At what temperature does water boil on Mount Everest? So-called "Steam pressure tables" provide information about this. It would also be interesting to refer to the phase transition points as temperature critical points. At the phase transition from liquid to gaseous the energy applied does not initially lead to an increase in temperature. The same applies to the melting of ice. Not until all the water has evaporated or melted does the temperature rise further.

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Siemens Stiftung

Sound diffraction

Graphic:
Diffraction is a typical feature of sound waves when they meet an obstacle.

The diffraction of sound waves is a physical mechanism which ensures the entry of sound waves into acoustic shadows.
That means the sound is audible in areas which are cut off from the direct sound incidence, such as behind obstacles.

Information and ideas:
Diffraction of light can be proved when a parallel ray beam of monochrome light is directed at a narrow opening. A screen set up behind the opening gives us a diffraction figure (bright and dark stripes that lose intensity the further outwards they are). With sound, a direct reference to the students' everyday world is even easier: Why can you hear noise from a street in front of a building even when you are behind the building?
Further information about this graphic is provided as an information sheet on the media portal of the Siemens Stiftung.

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

Medientypen

Bild

Lernalter

13-18

Schlüsselwörter

Chart Optics Sound Wave (physics)

Sprachen

Englisch