How wavelength & frequency calculator works
Every wave obeys the same kinematic relation: speed equals frequency times wavelength, v = f·λ. Wavelength is the spatial repeat length of the wave and frequency counts cycles per second, so their product is how far the pattern travels each second — the wave speed. For light in vacuum that speed is c = 299,792,458 m/s exactly; for sound in dry air at 20 °C it is about 343 m/s. Pick the medium, enter any two of the three quantities, and the third follows.
The tool adds the derived companions that make wave problems click: period (T = 1/f, the duration of one cycle), wavenumber (1/λ, cycles per metre), and — for light — photon energy. Because light is quantised, each photon carries E = hf, where h = 6.626×10⁻³⁴ J·s is Planck’s constant. The energy is reported in joules and in electronvolts, the unit spectroscopists actually use: 550 nm green light works out to about 2.25 eV per photon.
If you enter both a frequency and a wavelength, the tool computes the wave speed the pair implies — handy for checking a medium: 440 Hz with a 0.78 m wavelength implies 343.2 m/s, essentially the speed of sound in air, while the same math with light-speed frequencies exposes EM waves. Constants are exact SI defining values (c and h) or the standard 20 °C sound speed, and results are rounded to six significant figures.