Spectrum

• 50-60 Hz: electrical power frequency
• acoustical spectrum
  • ~20 Hz - ~20 kHz: sound (hearing)
  • 20 kHz - 100 MHz: ultrasound
• electromagnetic spectrum
  (band ranges are approximate, terminology varies, and frequency-band regulations vary from country to country)

  < 3 × 109 Hz	radio 535-1605 kHz: commercial AM radio 1.8-2, 3.5-4, 7-7.3, 14-14.35 MHz, etc (27 bands): amateur radio ~27 MHz: CB (Citizens Band) radio 88-108 MHz: commercial FM radio 54-72, 76-88, 174-216, 470-608, 614-890 MHz: television 902-928 MHz: cellular telephones 2.4-2.4835 GHz: unlicensed Industry, Science & Medicine band (microwave ovens use 2.45 GHz)
  3 × 109 - 3 × 1012 Hz	microwaves 5.725-5.85 GHz: broadband telecommunications ~10 GHz: radar
  3 × 1012 - 4.3 × 1014 Hz	infrared
  4.3 × 1014 - 7.5 × 1014 Hz	visible
  7.5 × 1014 - 3 × 1017 Hz	ultraviolet UV-A: 315-400 nm (least harmful; "black light") UV-B: 280-315 nm (more harmful, absorbed by ozone) UV-C: 100-280 nm (most harmful, absorbed by air)
  3 × 1017 - 3 × 1019 Hz	x-rays
  > 3 × 1019 Hz	gamma rays