PHYSICS / QUANTUM PHYSICS
Calculate a particle's characteristic Compton wavelength from its rest mass using exact SI constants.
METHOD / WORKED EXAMPLE
Compton wavelength is a characteristic quantum-relativistic scale fixed by particle rest mass; no particle speed or beam energy is entered.
WORKED DEFAULT
Using the electron rest mass 9.10938e-31 kg, h divided by mc gives 2.42631e-12 m, which is 2.42631 pm.
READ THE RESULT
A smaller rest mass produces a larger Compton wavelength. Do not substitute this output for a moving particle's de Broglie wavelength or for the wavelength shift at an arbitrary scattering angle.
ASSUMPTIONS AND LIMITS
The result is the unreduced Compton wavelength h over mc, not h-bar over mc and not a de Broglie wavelength set by particle speed.
Use internally consistent units and retain extra precision when carrying the result into another calculation.
COMMON QUESTIONS
No. Compton wavelength h over mc is a fixed characteristic scale determined by rest mass. De Broglie wavelength h over p depends on the particle's momentum and therefore its motion. They can be related in some analyses, but the inputs and physical interpretation are different.
The reduced Compton wavelength uses h-bar over mc, so it is the unreduced value divided by two pi. This calculator intentionally reports h over mc because that is the factor appearing in the OpenStax Compton-shift expression. Check which convention a formula requires before making any numerical substitution.
Not completely. The Compton shift is the characteristic wavelength multiplied by one minus the cosine of the photon scattering angle. This page returns only the particle-dependent characteristic factor. A scattering calculation also needs a defined angle and the free-particle collision assumptions used in the conservation derivation.
RELATED TOOLS
Use boundary
Divide the exact Planck constant by rest mass times the exact vacuum speed of light. The page evaluates the displayed equation from your supplied values and presents both symbolic and substituted KaTeX working so the arithmetic can be checked.
lambda_C = h / (mc)