Formula De Broglie wavelength Mass Velocity
$$\lambda ~=~ \frac{h}{m \, v}$$ $$\lambda ~=~ \frac{h}{m \, v}$$ $$m ~=~ \frac{h}{v \, \lambda}$$ $$v ~=~ \frac{h}{m \, \lambda}$$
De Broglie wavelength
$$ \lambda $$ Unit $$ \mathrm{m} $$ Every particle of mass \(m\) (e.g. electron, proton) can be assigned a wavelength \( \lambda \) in quantum mechanics, the so-called matter wavelength (also called De-Broglie wavelength). De-Broglie wavelength determines the interference ability of particles.
Here \( m \, v \) is the momentum \(p\) of the particle.
Mass
$$ \class{brown}{m} $$ Unit $$ \mathrm{kg} $$ Mass of the particle. Heavy particles have a shorter matter wavelength than light particles.
Velocity
$$ v $$ Unit $$ \frac{\mathrm m}{\mathrm s} $$ Velocity with which the considered particle moves. Fast particles have a shorter matter wavelength than slow particles.
Planck's Constant
$$ h $$ Unit $$ \mathrm{Js} = \frac{ \mathrm{kg} \, \mathrm{m}^2 }{ \mathrm{s} } $$ Planck's constant is a physical constant (of quantum mechanics) and has the value:$$ h = 6.626 \, 070 \, 15 \,\cdot\, 10^{-34} \, \mathrm{Js} $$