We have demonstrated that light is both a wave and a particle. In 1924, Louis de Broglie suggested that not only is light both a particle and a wave, but all particles have both wavelike and particle-like properties. Within a short time, Davisson and Germer reported that electrons diffract through crystals in a manner similar to x rays. The relation between the wavelength and momentum of the particle is given by
This wavelength is called the de Broglie wavelength of a particle. Macroscopic objects have a very short wavelength. For example, a baseball thrown at 100 miles per hour has a wavelength of 1.05 x 10-34 m. This wavelength is very small even when compared to atomic sizes (10-10 m) and nuclear sizes (10-15 m.) Even a very slow-moving macroscopic object has a very small wavelength.
Electrons are often used as probes to study atomic and nuclear systems. The electron must have sufficient energy to produce a de Broglie wavelength smaller than the system to be studied. For example, for an electron to have a wavelength of 10-11 m is must have an energy of 15,000 eV.
© MultiMedia Physics 2000