Unit Conversion Calculator

Wavelength Calculator

Switch between light, sound in dry air, and a custom wave speed. Results update as you type.

Explore wavelength, frequency and speed

Switch between light, sound in dry air, and a custom wave speed. Results update as you type.

Wave type

Light and radio waves

In a medium, light slows and its wavelength changes; its frequency stays the same. Use 1 for a vacuum.

Calculate

Calculated values

Wave speed—
Frequency—
Wavelength—

Calculation steps

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Wavelength in other units

Wave illustration

λ

Illustration only; the drawing is not to scale.

Electromagnetic spectrum

RadioMicrowaveInfraredVisibleUltravioletX-rayGamma ray

Approximate bands, based on wavelength in a vacuum.

NASA: Light and radio waves · NASA: Sound in dry air

Understanding Wavelength

Wavelength (\(\lambda\)) is a fundamental concept in physics, particularly in wave mechanics. It is defined as the distance between two successive crests or troughs of a wave. The wavelength is inversely proportional to the frequency (\(f\)) of the wave and directly proportional to the speed (\(v\)) of the wave. This relationship is described by the following equation:

\[ \lambda = \frac{v}{f} \]

Where:

  • \(\lambda\) is the wavelength in meters (m).
  • \(v\) is the speed of the wave in meters per second (m/s).
  • \(f\) is the frequency of the wave in hertz (Hz).

Deriving the Equations

From the fundamental relationship \(\lambda = \frac{v}{f}\), we can derive the other two equations:

\[ v = \lambda \times f \] \[ f = \frac{v}{\lambda} \]

Using the Wavelength Calculator

To use the Wavelength Calculator, enter any two of the three values (speed, frequency, or wavelength) and select their respective units. Click the “Calculate” button to determine the missing value.

Example 1

Suppose you have a wave traveling at a speed of \(3 \times 10^8\) m/s (the speed of light) with a frequency of 500 MHz. To find the wavelength:

\[ \lambda = \frac{3 \times 10^8 \text{ m/s}}{500 \times 10^6 \text{ Hz}} = 0.6 \text{ m} \]

Example 2

If you know the speed of the wave is 1,000 m/s and the frequency is 2 kHz, you can calculate the wavelength:

\[ \lambda = \frac{1,000 \text{ m/s}}{2,000 \text{ Hz}} = 0.5 \text{ m} \]

Example 3

Given a speed of 50 km/h and a frequency of 10 Hz, you can find the wavelength. First, convert 50 km/h to m/s:

\[ 50 \text{ km/h} = 50 \times \frac{1000 \text{ m}}{3600 \text{ s}} = 13.889 \text{ m/s} \]

Then calculate the wavelength:

\[ \lambda = \frac{13.889 \text{ m/s}}{10 \text{ Hz}} = 1.3889 \text{ m} \]

Example 4

If you know the wavelength is 0.6 m and the frequency is 500 MHz, you can calculate the speed:

\[ v = 0.6 \text{ m} \times 500 \times 10^6 \text{ Hz} = 3 \times 10^8 \text{ m/s} \]

Example 5

Given a wavelength of 1.3889 m and a speed of 50 km/h, you can find the frequency. First, convert 50 km/h to m/s:

\[ 50 \text{ km/h} = 50 \times \frac{1000 \text{ m}}{3600 \text{ s}} = 13.889 \text{ m/s} \]

Then calculate the frequency:

\[ f = \frac{13.889 \text{ m/s}}{1.3889 \text{ m}} = 10 \text{ Hz} \]

Applications of Wavelength

Wavelength Calculator Image

Wavelength is used in various applications, including:

  • Electromagnetic Spectrum Analysis: Understanding different wavelengths helps in analyzing and categorizing electromagnetic waves, from radio waves to gamma rays.
  • Acoustic Wave Propagation: In sound engineering, wavelength is crucial for designing concert halls, speakers, and microphones.
  • Seismic Wave Studies: Seismologists use wavelength to study earthquakes and understand the structure of the Earth.

Final notes

Understanding the relationship between wavelength, frequency, and speed is crucial in many fields of science and engineering. The Wavelength Calculator simplifies the process of calculating these values, making it easier to apply these principles.

Choose the right wave model

For light in a medium, enter its refractive index. For sound, the air-temperature model is an approximation. Use custom speed for other media.

Read the calculation

The calculator converts your input to SI units before applying speed = frequency × wavelength. Unit equivalents are calculated from the same result.

Wavelength calculator questions

How do I calculate wavelength?

Choose the wave type, select wavelength as the result, and enter a frequency. The speed is set by the chosen model or by your custom value.

Does light keep the same frequency in another medium?

Yes. In this simplified model, frequency stays constant while speed and wavelength change with the refractive index.

Can I use the sound setting for water?

No. The sound preset estimates dry air only. For water or another medium, select custom wave speed and enter a suitable value.