Davisson-germer Experiment

NCERT describes the Davisson-Germer experiment as the landmark demonstration that electrons, long regarded as particles, also exhibit wave behaviour. When a collimated electron beam struck a nickel crystal, the scattered electrons showed a pronounced intensity peak at a specific angle, exactly the kind of constructive interference expected when waves diffract from the regularly spaced atomic planes of a crystal. The measured wavelength matched de Broglie's prediction $\lambda =\frac{h}{p}$, providing direct experimental proof of matter waves. The option about measuring rest mass is wrong because the experiment concerned diffraction geometry, not mass determination. The option about proving electron charge is wrong because charge had already been established by earlier experiments like Millikan's oil drop. The option about light behaving as particles is wrong because this experiment addressed electrons behaving as waves, the complementary side of duality. As stated in NCERT Class 12, Chapter 11, the agreement between the observed and de Broglie wavelengths confirmed the wave nature of electrons. A consistency check confirms that a diffraction peak at a definite angle is a signature only a wave, not a classical particle, could produce.