\(\bullet\) X = h / mv. This equation implies that a moving particle can be considered as a wave and a wave can exhibit the properties of a particle.

\(\bullet\) For a particle with high linear momentum (mv) the wavelength will be so small and cannot be observed.

\(\bullet\) For a microscopic particle such as an electron, the mass is of the order of 10^{-31} kg, hence the wavelength is much larger than the size of atom and it becomes significant.

\(\bullet\) For the electron, the de Broglie wavelength is significant and measurable while for the iron ball it is too small to measure, hence it becomes insignificant.