The significance of 54 volts in the Davisson-Germer experiment is that it corresponds to the accelerating voltage at which a pronounced diffraction pattern is observed, specifically at a scattering angle of 50 degrees. At this voltage, the electrons' momenta and de Broglie wavelength align to produce the first maximum in the intensity diagram. Deviating from 54 volts, either lower or higher, results in a displacement of the first maximum and alters the intensity pattern. This phenomenon is further explained by the electrons' index of refraction, which affects their behavior as they exit the crystal.
PREREQUISITESPhysicists, materials scientists, and students studying quantum mechanics or solid-state physics will benefit from this discussion, particularly those interested in electron diffraction and its implications in experimental physics.
"These results, including the failure of the data to satisfy the Bragg formula, are in accord with those previously obtained in our experiments on electron diffraction. The reflection data fail to satisfy the Bragg relation for the same reason that the electron diffraction beams fail to coincide with their Laue beam analogues. These differences between the electron and x-ray phenomena can perhaps be accounted for by assuming, as first suggested by Eckart,' that the crystal is characterized by an index of refraction for electrons as it is for x-rays, and that for electrons of the speeds used in our experiments the index has values which are quite different from unity.