Extremely low frequency (ELF) is pronounced ɪkˈstriːmli ləʊ ˈfrekwənsi. The first syllable of "extremely" is stressed, while the second and third syllables are pronounced with the schwa sound. "Low" is pronounced with the ow diphthong, and "frequency" is pronounced with the ee sound in the second syllable and si sound in the last syllable. IPA phonetic transcription helps to explain the spelling of the word "extremely low frequency" so that people can accurately and confidently pronounce and spell it.
Extremely Low Frequency (ELF) is a term used in physics and communication to describe a range of electromagnetic waves with frequencies between 3 and 30 hertz (Hz). These waves have the longest wavelengths and therefore the lowest frequencies within the spectrum of electromagnetic radiation. ELF waves are known for their ability to propagate over very large distances due to low atmospheric attenuation and the Earth's curvature. They have been extensively utilized in various military, scientific, and communication applications.
ELF waves are primarily used for long-distance communication with submarines, as they can penetrate marine layers that absorb higher frequency signals. Moreover, ELF waves can penetrate the Earth's surface, making them beneficial for geophysical exploration and monitoring activities.
In terms of health and environment, extremely low-frequency electromagnetic fields (ELF-EMFs) have attracted attention due to their potential effects on living organisms. Studies have explored the biological effects of ELF-EMFs on humans and other animals, particularly regarding long-term exposure. Though the evidence remains inconclusive, some research suggests possible links between ELF-EMFs and adverse health outcomes such as disruption of sleep patterns, changes in hormone levels, and increased cancer risk.
Overall, extremely low frequency refers to a range of electromagnetic waves with frequency values between 3 and 30 Hz, which exhibit unique propagation characteristics and find applications in communication, military operations, geophysical exploration, and scientific research.