Engineering Physics

4.1 Waves and particles — de Broglie hypothesis — Matter waves

Classical theory of Newtonian mechanics successfully explains the motion of macroscopic particles, but fails to explain the motion of microscopic particles such as electrons. Whereas, the quantum theory successfully explains the motion of microscopic particles, interference, diffraction and polarization of electromagnetic waves, black body radiation (1901), photoelectric effect (1905), line spectra (1913) and Compton effect (1924), etc. Explanation of the above effects by quantum theory shows the dual nature of waves [wave nature and particle nature]. To explain some of the above facts, we consider packets of energy [photons] and waves. For example, in case of photoelectric effect ...