Extremely low frequency (ELF)

Definition

Extremely low frequency (ELF) refers to electromagnetic waves with frequencies ranging from 3 Hz to 30 Hz. These frequencies are commonly used for communication with submarines and in certain geophysical applications.

5 Must Know Facts For Your Next Test

1. ELF waves have wavelengths that can range from 10,000 km to 100,000 km.
2. Due to their long wavelengths, ELF waves can penetrate deep into water and earth, making them useful for submarine communication.
3. Generation of ELF waves typically requires large antennas and significant power output.
4. The U.S. Navy has used ELF transmissions for secure communication with its submarine fleet.
5. ELF waves are at the lowest end of the electromagnetic spectrum in terms of frequency.

Review Questions

• What is the frequency range of Extremely Low Frequency (ELF) waves?
• Why are ELF waves suitable for communication with submarines?
• What is one major practical application of ELF waves?

Related terms

Electromagnetic Spectrum: The range of all types of electromagnetic radiation, ordered by frequency or wavelength.

Frequency: The number of oscillations or cycles per second of a wave, measured in Hertz (Hz).

Wavelength: The distance between consecutive peaks or troughs in a wave, inversely related to frequency.