EM Spectrum
The full electromagnetic spectrum from radio waves to gamma rays.
VLF radio waves (3–30 kHz) used for submarine communication and navigation. Can penetrate seawater.
AM radio broadcasts (530 kHz – 1.7 MHz). Amplitude modulation, discovered in the early 20th century. Long range, especially at night.
FM radio (88–108 MHz). Frequency modulation provides higher fidelity audio than AM. Line-of-sight transmission.
WiFi 2.4 GHz band used for wireless networking. Part of the ISM (Industrial, Scientific, Medical) band.
Standard microwave oven frequency (2.45 GHz). Causes water molecules to rotate, generating heat. Same ISM band as WiFi.
Near infrared radiation (~300 THz, ~1000 nm). Used in remote controls, fiber optics, and night vision. Just beyond visible red light.
Red visible light at ~620 nm wavelength. Lowest frequency of visible light. Red light therapy is used for skin healing and inflammation.
Green visible light at ~530 nm. The human eye is most sensitive to green light. Peak sensitivity of photopic vision.
Blue visible light at ~470 nm. Blue light suppresses melatonin production and affects circadian rhythms. Used in SAD light therapy.
Violet light at the highest visible frequency (~380 nm). At the boundary with ultraviolet radiation.
UV-A radiation (315–400 nm). Causes skin tanning and aging. Not fully blocked by atmosphere.