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Siemens Stiftung

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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Siemens Stiftung

Sound refraction

Schematic diagram:
Sound refraction in air with different temperature layers (from warm to cold).

The speed of sound in the air depends on the density and thus the temperature of the air: At high temperatures, the sound travels faster than it does at lower ones. So when sound moves from a warm layer of air to a colder one, its speed decreases.
However, the direction in which the sound spreads also changes as the speed changes. It is said that the sound wave is "broken?. In the case described, i.e. when sound moves from a warm to a cold layer of air, the sound wave is broken upwards.

Information and ideas:
How does sound behave when it moves from a colder to a warmer layer?
Is it correct that you hear worse against the wind than with the wind?
The latter can be checked together with students in an experiment.
A comparison with the refraction of light rays can be made.

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

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Siemens Stiftung

Magnetic energy

Overview graphic:
Two manifestations of magnetic energy are compared: the magnetic energy of a current-bearing coil and that of an elementary magnet.

Magnetic energy is the energy that is stored in a current-bearing coil in the form of its magnetic field. It is the result of the work that the current has to perform in opposition to the induced voltage (Faraday?s law of induction). Conversely, this magnetic energy is released again in the form of electric current when the magnetic field collapses. Magnetic energy is also stored in a magnetized material. It is equivalent to the work that must be expended in order to align the magnetic dipoles of this material in an external magnetic field. In ferromagnetic materials, the magnetic dipoles align themselves in small zones ("Weiss domains"), even without an external magnetic field. If the Weiss domains are now aligned by an external magnetic field, a permanent magnet is produced.
Incidentally: If a permanent magnet is heated above a critical temperature, it loses its magnetization. The magnetic energy is released as additional heat at this so-called Curie temperature.

Information and ideas:
A simple experiment on magnetization: If you pass a permanent magnet over an iron nail, it magnetizes the nail. What work has to be expended for this, apart from the friction work? Is the permanent magnet or its magnetic energy "used up" in the process?

Anderer Ressourcentyp

Siemens Stiftung

Popular hobbies among children (answer sheet)

Answer sheet:
For the worksheet of the same name.

Information and ideas:
You can find more detailed information on the associated worksheet "Popular hobbies among children," which is available on the media portal of the Siemens Stiftung.

Anderer Ressourcentyp

Siemens Stiftung

What are the most popular hobbies among children?

Bar chart:
As one possible way to represent statistics, a bar chart based on the example of popular hobbies among children is presented.

The chart shows five fictitious values for the number of children who pursue the hobbies of dancing, soccer, horseback riding, reading, swimming, and computer gaming. It is used to teach the students how to read simple charts and how to gather information from them. The students can use this example to practice the terminology (more/fewer than, same number, the fewest/most).

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Siemens Stiftung

The Ear, Hearing and Hearing Impairment;: Vibrations and waves

Overview graphic:
Overview of the most important parameters of vibrations and waves.

Electromagnetic waves are vibrations in the electrical and magnetic field that propagate through space at the speed of light. The parameters of vibrations and waves, such as frequency, are presented in an overview.

Instructions and ideas:
As overview information for students on the topic of "vibrations and waves". Important basis for understanding sound waves in acoustics.

Medientypen

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Lernalter

11-18

Schlüsselwörter

Chart Optics Sound Wave (physics)

Sprachen

Englisch

Dieses Material ist Teil einer Sammlung

Anderer Ressourcentyp

Siemens Stiftung

Energy consumption - comparison between countries

Matching exercise:
The countries China, the United States, Russia, Norway, Germany, Kenya, and the world as a whole are compared in terms of energy production, total energy consumption, and energy consumption per capita. Why does consumption vary so widely?

The chart shows, for example, that China consumes more energy as a whole than the United States, but per-capita consumption is significantly lower. Norwegians have much higher per-capita consumption than Germans. Why is that? Possible answers: The price of electricity is much lower in Norway and households often use storage heaters. The students should match the factors with the listed countries where they play a main role in energy consumption.

Information and ideas:
The bar chart is based on comparison values from 2011; the unit for production and consumption is million of tonnes of oil equivalent (mtoe), and the unit for per-capita consumption is kilogram of oil equivalent (kgoe). The answers to the following questions can be deduced from the chart: Which countries produce more energy than they consume? Which country has the highest per-capita consumption?
The exercise is designed as an "open exercise?; an answer sheet is not provided. The students? matches can encourage discussion. Inquiry tasks for the respective countries can also be assigned to the students. After they have presented their results, the students can check their initial matches.


Dieses Material ist Teil einer Sammlung