- What are electromagnetic fields?
- Static and low-frequency fields
- What are static and low-frequency electric and magnetic fields?
- Direct and alternating voltage
- Effects of static and low-frequency fields
- Reports & Evaluations
- Radiation protection relating to the expansion of the national grid
- Basics transfer of electrical power
- High-frequency fields
- What are high-frequency fields?
- Applications high-frequency fields
- Radiation protection in mobile communication
- What is mobile communication?
- Reports and evaluations
- What is optical radiation?
- UV radiation
- What is UV radiation?
- Sun but safe!
- Effects of UV radiation
- Protection against UV radiation
- UV index
- Infrared radiation
- What is ionising radiation?
- Radioactivity in the environment
- Where does radioactivity occur in the environment?
- What is the level of natural radiation exposure in Germany?
- Air, soil and water
- Building materials
- Industrial residues (NORM)
- BfS laboratories
- Applications in medicine
- Radiation protection in medicine: international activities
- Applications in daily life and in technology
- Radioactive radiation sources in Germany
- Register high-level radioactive radiation sources
- Type approval procedure pursuant to RöV and StrlSchV
- Cabin luggage security checks
- Radioactive materials in watches
- Ionisation smoke detectors (ISM)
- What are the effects of radiation?
- Effects of selected radioactive materials
- Consequences of a radiation accident
- Cancer and leukaemia
- Genetic radiation effects
- Individual radiosensitivity
- Epidemiology of radiation-induced diseases
- Ionising radiation: positive effects?
- Risk estimation and assessment
- Radiation protection
- Basic information
- Occupational radiation protection
- Nuclear accident management
- What is an emergency?
- What happens in an emergency?
- Federal and state tasks
- In the event of an emergency
- Measuring networks
- Exercises for emergency situations
- Defence against nuclear hazards
- Service offers
- Radon measurements
- Incorporation monitoring
- Biological dosimetry
- Online library
- About us
- Science and research
- Research concept
- Scientific collaborations
- EU research framework programme
- BfS research programme
- Third-party funded research
- Departmental research
- Selected research projects
- Selected research results
- Professional opinions
- Science Council
- Laws and regulations
- BfS Topics in the Bundestag
What are electromagnetic fields?
- Electric and magnetic fields describe the spatial distribution of a force which can act upon electric charges and currents.
- Electromagnetic fields can be generated artificially, but also occur naturally in the environment. They belong to "non-ionising radiation".
- With static and low-frequency fields the electric and the magnetic components are considered separately. In the case of high-frequency fields the two components are closely interrelated and are referred to as electromagnetic fields.
- Low-frequency electric and magnetic fields can produce electric fields and currents in the human body. High-frequency electromagnetic fields can heat up biological tissue.
- It is the task of radiation protection to ensure that the strengths of the fields are so low that no health damage occurs.
Electromagnetic fields are part of the electromagnetic spectrum. Over its entire range, the spectrum extends from static electric and magnetic fields over optical radiation to very energetic gamma radiation. For the part of the spectrum in between static electric and magnetic fields and infrared radiation, the generic term "electromagnetic fields" is common.
When do we speak of fields and when of waves or radiation?
Instead of the term "electromagnetic fields", the expressions "electromagnetic waves" or "electromagnetic radiation" are also used. The various terms describe different physical properties:
- "field" describes the spatial distribution of a force which can act upon electric charges and currents
- "wave" describes the propagation of a time-varying field in space
- "radiation" describes the transport of energy.
How are electromagnetic fields categorized?
In the same way as the entire electromagnetic spectrum is divided into regions, electromagnetic fields are categorized into different types based on their physical properties. This is done either
- according to their frequencies or
- according to their wavelengths.
The unit of measurement for frequency is Hertz (Hz; 1 Hz = 1 oscillation per second). The wavelength is specified in meters (m). Frequency and wavelength are interlinked by the velocity of propagation. At high frequencies the wavelengths are small, whereas low frequencies are associated with large wavelengths.
|Static electric and magnetic fields||0 hertz||--|
|Low-frequency electric and magnetic fields||above 0 hertz up to 100 kilohertz (kHz)||more than 300.000 kilometers to 3 kilometers|
|high-frequency electromagnetic fields||100 kilohertz to 300 gigahertz (GHz)||3 kilometers to 1 millimeter|
Frequencies above 300 gigahertz are generally referred to as "radiation". The term "field" is not used for this range of the spectrum.
Why do we differentiate between static and low-frequency electric and magnetic fields and high-frequency electromagnetic fields?
With static and low-frequency fields the electric and the magnetic components are considered separately. In the case of high-frequency fields the two components are closely interrelated and are referred to as electromagnetic fields. As the various ranges of electromagnetic fields have different physical properties, also their effects on biological organisms differ.
Where do we find static, low-frequency and high-frequency fields?
- A naturally occurring static field is the Earth’s magnetic field.
- In the atmosphere, between the Earth and the ionosphere, there is a permanent electric field: the fair weather field.
- Artificial low-frequency electric fields are present around all electrical wires and appliances to which a voltage is applied.
- Low-frequency magnetic fields occur around all electrical appliances and wires with alternating current flowing through them.
- High-frequency electromagnetic fields are used in mobile communications, WLAN or cordless phones, for example.
What are the effects of electromagnetic fields?
Due to their different physical properties, the various ranges of the electromagnetic spectrum have different effects on biological organisms. In the process, the energy of the individual photons is particularly significant. It increases constantly with increasing frequency.
Electromagnetic fields belong to "non-ionising radiation". In contrast to ionising radiation, the photons of non-ionising radiation do not have enough energy to ionise atoms and molecules, that is, to "eject" electrons from the shells and to produce positively charged particles (ions) as a result. Among other things, this means that – in contrast to X-radiation – their energy is too low to cause direct damage to genetic material and for being directly involved in the development of cancer.
However, electromagnetic fields can cause health damage in other ways:
- Low-frequency electric and magnetic fields can produce electric fields and currents in the human body.
- High-frequency electromagnetic fields can heat up biological tissue.
It is the task of radiation protection to ensure that the strengths of the fields are so low that no health damage occurs.
State of 2018.03.15