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Similar to the crystal diffraction patterns produced by X-rays, even the beam of electrons of appropriate momentum could produce crystal diffraction pattern. Imparting the desired momentum to the electron obtained by thermionic emission from a heated filament was done by electrostatic acceleration. As electron accelerated through a potential difference of 'V' volts, acquires a kinetic energy.
According to work energy principle, work done on the electron appears as the gain in the kinetic energy of the electron
De-Broglie wavelength associated with moving electron is given by
Substituting h = 6.62 x 10
-34Js, m = 9.1x 10
-31Kg and e=1.6x10
-19, we get
For an electron accelerated through 100 volts, the wavelength is 1.225 x 10-10m. Thermal neutrons also have wavelength of the same order say around 1.5 x 10-10m. But in contrast the wavelength of one gram mass with the same thermal energy has the fantastically small value about 1.2 x 10-22m. There is no wonder then the macroscopic objects show no noticeable diffraction effects.
