What frequency range does Extremely Low Frequency (ELF) cover?

• A. 1 to 30 Hertz
• B. 30 to 300 Hertz
• C. 300 to 3000 Hertz
• D. 3 to 30 Kilohertz

Answer: (A)

Extremely Low Frequency (ELF) refers to a specific range of radio frequencies in the electromagnetic spectrum. This range is defined as covering frequencies from 1 to 30 Hertz. ELF waves are utilized in various applications, including communication with submarines and geological monitoring. The low frequency allows these waves to penetrate deep into water and the earth, making them suitable for long-distance communication in challenging environments. The correct answer reflects the established definition of ELF as specified by various standards in telecommunications and electromagnetic frequency categories.

The other ranges presented do not represent the ELF category; instead, they correspond to different frequency classifications like Very Low Frequency (VLF) or Low Frequency (LF), which serve other communication purposes.