The electromagnetic spectrum is a continuum of electromagnetic waves arranged in order of increasing frequency or decreasing wavelength. The lowest frequency in the electromagnetic spectrum is associated with radio waves. Radio waves have the longest wavelengths and the lowest frequencies among all the types of electromagnetic waves.
The lowest radio frequencies range from a few Hertz (Hz) to several kilohertz (kHz). These frequencies are used for long-range communications, such as AM (amplitude modulation) radio broadcasting and some navigation systems.
Below the radio wave frequencies, there are even lower frequencies that fall into the category of Extremely Low Frequency (ELF) waves. ELF waves have frequencies ranging from a few Hz to a few tens of Hz. They are used in some specialized applications, including certain military communications systems and scientific research.
It's important to note that the electromagnetic spectrum is vast, and it covers a wide range of frequencies and applications. As you move up the spectrum, the frequencies increase, and the wavelengths decrease, leading to other types of waves like microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Each portion of the spectrum has its own characteristics, applications, and interactions with matter.