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Siemens Stiftung

;: Chemical energy

Chart:
Chemical energy as binding energy between atoms (as a potential curve in the illustration).

Chemical energy is present both in the bond between atoms and molecules as well as in the potential for chemical bonding. This energy can be released in the form of heat during the bonding process or when those bonds are broken. This "heat of reaction" is also referred to as reaction enthalpy (H). The release of heat (dH < 0) is referred to as an exothermic reaction. An endothermic reaction is when heat is absorbed (dH > 0).
Every mixture of source materials that can react to produce end products can be regarded as a potential source of chemical energy.
Microscopically speaking, this chemical energy can be found in the bonds between individual atoms, as illustrated in the potential curve.

Information and ideas:
Chemical energy is a form of energy that is easy to store - whether in the human body or in batteries. An additional example is hydrogen as a chemical energy store for renewable energy sources.

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Energy Saving: Energy saving as an energy source

Schematic diagram:
On the basis of selected examples, this overview demonstrates that energy saving itself can be described as an "energy source.?

Five examples from everyday life (electric power and heat generation, power distribution, construction, lighting, and transportation) are used to show how energy saving reduces the consumption of individual energy sources (primary or secondary).

Information and ideas:
Students can look for further examples. What is the significance of energy saving in relation to the general scarcity of resources? Can it be equated roughly with the harnessing of renewable energy sources?


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Stores for electrical energy

Overview graphic:
Examples for direct and indirect stores for electrical energy are shown and the stored energy form is designated.

Electrical energy should if possible be generated at precisely the time at which it is needed. This is because electrical energy is difficult and expensive to store. A distinction is made between direct and indirect stores for electrical energy. Electrical energy can only be stored directly in capacitors. With indirect storage, the electrical energy can be converted into a different form of energy which can then be stored.

Information and ideas:
Students should think about the economical use of the energy stores shown (for example: How much energy can be stored? Can the energy store be used without any problems? Where do losses occur?).

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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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Worldwide consumption of fossil energy sources

Chart and table:
The worldwide consumption of fossil energy sources and their use in electric power and heat generation in figures.

The pie chart displays the percentage share of fossil energy sources (coal, oil, and natural gas) in the worldwide primary energy supply. The table shows a breakdown by distribution of these fossil energy sources to electric power and heat generation, but also to other areas such as industry.

Information and ideas:
The chart and table provide the students with an overview of where and to what extent fossil energy sources were used in 2005. These aids can be followed by discussions on the finite nature of these energy sources and on changing over to or expanding the use of renewable energy sources. Additional information can be found in the "An overview of energy sources? information sheet and the "How long will our energy sources last?? graphic.

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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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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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Perforation of the eardrum

Labeled graphic:
Simplified illustration of a perforated eardrum.

A perforated eardrum can occur when foreign bodies, for example, instruments to clean the ears, are stuck in too far or when there are loud bangs near the ear.
Violent blows to the ear can also cause perforation.

Minor tears or perforations can heal up by themselves provided they get the proper treatment. In any case, a doctor should always be consulted!

Information and ideas:
Can be used for illustration purposes on the subject of "Ear diseases" either on transparencies or worksheets. Supposedly "harmless" minor problems can turn into serious damage to the ear.

Relevant for teaching:
Hearing defect/hearing impairment

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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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How long will our energy sources last?

Chart:
A bar chart shows an overview of the remaining years of use of primary energy sources.

Of the fossil energy sources, petroleum will be the first to run out. What is the situation for the other fossil energy sources? Can new technologies delay the point in time when they run out? And is it really true that renewable energy sources never run out?
The time axis has a logarithmic scale.

Information and ideas:
Students learn that the logarithmic scale represents numbers ranging over several powers. More in-depth information regarding how long energy sources will last is provided in the "An overview of energy sources? information sheet.


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