What is the wave equation?

v = f times lambda, where v is wave speed (m/s), f is frequency (Hz), and lambda is wavelength (m). Period T = 1/f. Enter any two values to solve for the others.

What is the frequency of visible light?

Visible light has wavelengths from about 380 nm (violet) to 700 nm (red). At the speed of light (3 times 10^8 m/s), violet light has frequency approximately 7.9 times 10^14 Hz and red light approximately 4.3 times 10^14 Hz.

What is the speed of sound?

Sound travels at approximately 343 m/s in air at 20 degrees C (68 degrees F). Speed increases with temperature and varies by medium: 1,480 m/s in water, 5,100 m/s in steel.

What is the difference between frequency and wavelength?

Frequency is how many wave cycles pass a point per second (Hz). Wavelength is the distance between consecutive crests (m). They are inversely related at constant wave speed: higher frequency means shorter wavelength.

Wavelength & Frequency Calculator

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The wave equation and its applications

All waves — light, sound, water, radio — obey v = f times lambda. For electromagnetic waves in vacuum, v = c = 2.998 times 10^8 m/s. For sound in air at 20 degrees C, v = 343 m/s. The medium determines the wave speed; the source determines the frequency; wavelength adjusts accordingly.

The electromagnetic spectrum spans from gamma rays (wavelength below 10^-12 m, frequency above 10^20 Hz) to radio waves (wavelength above 1 m, frequency below 10^9 Hz). Visible light occupies a tiny window: 380-700 nm. The calculator covers all of these with appropriate unit selectors.

Period, frequency, and their relationship

Period (T) is the time for one complete wave cycle in seconds. Frequency (f) is the number of cycles per second in Hz. They are reciprocals: f = 1/T, T = 1/f. A 440 Hz musical note (A4) has a period of 1/440 = 2.27 milliseconds.

The Doppler effect shifts the observed frequency when source or observer moves. A source moving toward you raises the observed frequency (shorter wavelength, higher pitch); moving away lowers it. This is why an ambulance siren sounds higher pitched as it approaches and lower as it recedes.

Frequently asked questions

What is the wave equation?: v = f times lambda, where v is wave speed (m/s), f is frequency (Hz), and lambda is wavelength (m). Period T = 1/f. Enter any two values to solve for the others.
What is the frequency of visible light?: Visible light has wavelengths from about 380 nm (violet) to 700 nm (red). At the speed of light (3 times 10^8 m/s), violet light has frequency approximately 7.9 times 10^14 Hz and red light approximately 4.3 times 10^14 Hz.
What is the speed of sound?: Sound travels at approximately 343 m/s in air at 20 degrees C (68 degrees F). Speed increases with temperature and varies by medium: 1,480 m/s in water, 5,100 m/s in steel.
What is the difference between frequency and wavelength?: Frequency is how many wave cycles pass a point per second (Hz). Wavelength is the distance between consecutive crests (m). They are inversely related at constant wave speed: higher frequency means shorter wavelength.