Electromagnetic Spectrum

/ɪˌlɛktroʊmæɡˈnɛtɪk ˈspɛktrəm/

noun … “Range of all possible electromagnetic wave frequencies.”

Electromagnetic Spectrum is the continuum of all electromagnetic radiation frequencies, from extremely low-frequency waves used in power lines to extremely high-frequency gamma rays. Each portion of the spectrum is characterized by its wavelength, frequency, and energy, dictating how it interacts with matter and how it can be harnessed for communication, sensing, or energy transfer. The spectrum encompasses radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

Key characteristics of the Electromagnetic Spectrum include:

• Frequency-wavelength relationship: frequency (f) and wavelength (λ) are inversely related through the speed of light, c, as λ = c / f.
• Propagation properties: lower frequencies (long wavelengths) penetrate obstacles and travel long distances, while higher frequencies (short wavelengths) carry more information but are more easily absorbed or scattered.
• Energy: higher frequency waves carry more photon energy, influencing applications in imaging, heating, and radiation therapy.
• Regulatory allocation: specific portions of the spectrum are allocated for communication services, scientific research, and industrial use to avoid interference.
• Applications: includes Radio communications, microwave links, infrared sensing, visible-light optics, ultraviolet sterilization, X-ray imaging, and gamma-ray astronomy.

Workflow example: In a wireless system, engineers select an appropriate frequency band based on required range, data rate, and penetration. For example, 2.4 GHz radio waves (λ ≈ 0.125 meters) provide reasonable indoor coverage and moderate data rates, while millimeter-wave bands in 5G (28 GHz, λ ≈ 0.0107 meters) offer higher throughput but require line-of-sight propagation.

-- Example: wavelength calculation from frequency
speed_of_light = 3e8       -- meters per second
frequency = 2.4e9          -- 2.4 GHz
wavelength = speed_of_light / frequency
print("Wavelength: " + str(wavelength) + " meters")
-- Output: Wavelength: 0.125 meters

Conceptually, the Electromagnetic Spectrum is like a piano keyboard stretching infinitely, with each key representing a frequency. Different keys produce different “colors” or behaviors of waves, and humans design instruments and systems to play or listen to specific notes in this vast continuum.

See Radio, Wavelength, Antenna, Modulation, Signal-to-Noise Ratio.