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Calculate frequency, period, and wavelength for any wave — audio, radio, light, or electromagnetic. Convert between hertz, kilohertz, megahertz, and gigahertz. Essential for electronics engineers, radio operators, and physics students.
From the 60 Hz hum of AC power to the 5 GHz channels of WiFi 6, from the 20 Hz bass of a subwoofer to the 3 GHz operating speed of a modern CPU — frequency is the universal language of electronics and physics. Every oscillating signal, every periodic phenomenon, and every communication channel is defined by its frequency.
Frequency (f) is the number of cycles per second, measured in Hertz (Hz). Period (T) is the time for one complete cycle in seconds. Wavelength (λ) is the physical distance between wave crests. These three quantities describe every wave in nature — from audio to radio to light.
Frequency and period are exact reciprocals: f = 1/T and T = 1/f. A 50 Hz power supply completes 50 cycles per second, so each cycle takes T = 1/50 = 0.02 seconds (20 milliseconds). A 1 MHz radio signal completes 1,000,000 cycles per second, with T = 1 microsecond per cycle.
For electromagnetic waves (radio, light): λ = c/f where c = 299,792,458 m/s (speed of light). For sound waves: λ = v/f where v ≈ 343 m/s at 20°C. A 100 MHz FM radio signal has wavelength = 3×10⁸/10⁸ = 3 meters. A 440 Hz (A4 musical note) sound wave has wavelength = 343/440 = 0.78 meters.
| Frequency | Period | Wavelength | Application |
|---|---|---|---|
| 20 Hz | 50 ms | 17.15 m (sound) | Human hearing lower limit |
| 440 Hz | 2.27 ms | 0.78 m | Musical note A4 |
| 50 Hz | 20 ms | 6,000 km | AC power (Europe) |
| 2.4 GHz | 0.417 ns | 12.5 cm | WiFi / Bluetooth |
| 100 MHz | 10 ns | 3 m | FM Radio |
| 5G (28 GHz) | 0.036 ns | 10.7 mm | 5G mmWave |
Frequency is the fundamental parameter that defines radio bands, audio ranges, processor speeds, and communication protocols. Different frequency ranges have distinct propagation characteristics, applications, and regulatory requirements.
The RF spectrum is divided into bands: LF (30-300 kHz, AM navigation), MF (300kHz-3MHz, AM radio), HF (3-30 MHz, shortwave, amateur radio), VHF (30-300 MHz, FM radio, aircraft), UHF (300MHz-3GHz, TV, WiFi, 4G), SHF (3-30 GHz, 5G, radar, satellite). Each band has unique propagation: HF reflects off the ionosphere enabling global communication; UHF is line-of-sight only.
Quartz crystal oscillators provide extremely precise frequencies for clocks and communication systems. A 32.768 kHz crystal is used in watches (2^15 = 32768, convenient for binary counters). A 16 MHz crystal drives many Arduino microcontrollers. Crystals maintain frequency accuracy to ±50 ppm over temperature — far better than RC oscillators (±5%).
The Nyquist theorem states that to accurately digitize an analog signal, the sampling rate must be at least 2× the highest frequency. Audio CD quality uses 44.1 kHz sampling (covers up to 22.05 kHz — beyond human hearing at 20 kHz). 5G uses 100 MHz bandwidth channels requiring multi-GHz sampling rates in the baseband processors.