# de Broglie wavelength

An electron of energy

*E*and linear momentum*p*could be defined by a matter wave whose wavelength and frequency are given bywhere

*h*is Planckâ€™s constant. The wavelength of a moving particle calculated above is called its de Broglie wavelength.# Heisenbergâ€™s uncertainty principle

It is not possible to measure, simultaneously, the position and the momentum of a particle with unlimited precision. If âˆ†

*x*is the uncertainty in position and âˆ†*p*is uncertainty in momentum, then