Physics

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De Broglie Wavelength Calculator.

Calculate matter-wave wavelength from mass and speed using the non-relativistic momentum model.

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Set your values

Results update as you type.

Wavelength: 0 m

Wavelength

0.000000m
Momentum: 0 kg·m/s

Momentum

0.000000kg·m/s

Results update automatically as you type.

Use Cases

Physics homework and exam prep

Quickly verify de Broglie wavelength calculations for practice problems involving electrons, protons, or other particles moving at non-relativistic speeds.

Example: Calculate the wavelength of an electron moving at 1,000,000 m/s.

Understanding wave-particle duality

Explore how the wavelength changes with mass and speed, helping to grasp the concept that larger or faster particles have shorter wavelengths.

Example: Compare the wavelength of a baseball vs. an electron at the same speed.

Frequently Asked Questions

What is the de Broglie wavelength?
The de Broglie wavelength is the wavelength associated with a moving particle, given by Planck's constant divided by the particle's momentum (mass times speed). It shows that matter can exhibit wave-like behavior.
How do I use this calculator?
Enter the particle's mass in kilograms and its speed in meters per second. The calculator then computes the wavelength using the non-relativistic formula λ = h / (m * v), where h is Planck's constant.
Is this calculator valid for all speeds?
No, this calculator uses the non-relativistic momentum model, which is accurate for speeds much less than the speed of light. For speeds close to the speed of light, relativistic effects must be considered.

Tips & Common Mistakes

Tips

  • Ensure mass is in kilograms (kg) and speed in meters per second (m/s) to get the wavelength in meters.
  • For very small particles like electrons, the wavelength is often in the nanometer or picometer range, so convert to convenient units if needed.
  • Remember that this calculator is non-relativistic; for speeds above about 10% of the speed of light, use a relativistic calculator.
  • Double-check your inputs for scientific notation, as masses of subatomic particles are often given in powers of ten.

Common Mistakes to Avoid

  • Using mass in grams or speed in km/h without converting to kg and m/s, leading to incorrect results.
  • Applying this calculator to particles moving at relativistic speeds, where the non-relativistic formula is not accurate.
  • Confusing the de Broglie wavelength with the wavelength of light; this is for matter waves, not electromagnetic waves.

Last updated: August 13, 2026