9.2 Wave particle duality
9.2.1 Newton's corpuscular theory of light
Comparison with Huygens' wave theory in general terms
The reasons why Newton's theory was preferred
9.2.2 The significance of Young's double slits experiment
Explanation for fringes in general terms, no calculations are expected
Delayed acceptance of Huygens' wave theory of light
9.2.3 Electromagnetic waves
Nature of electromagnetic waves
Maxwell's formula for the Speed of electromagnetic waves in a vacuum
Michelson's measurement of the speed of light
Hertz's discovery of radio waves
9.2.4 Black body radiation
Black body radiation curves
Outline of the failure of classical wave theory; the ultra violet catastrophe
Planck's concept of energy quanta to explain black body radiation: E =hf
The significance of energy quantisation
9.2.5 The discovery of photoelectricity
Millikan's photoelectric experiment
The failure of classical wave theory to explain photoelectricity
The significance of Einstein's explanation of photoelectricity
photon energy = hf
9.2.6 Wave particle duality
De Broglie's
hypothesis
supported by
electron diffraction
experiments +
more notes
p=h
/
l
l =
h/
Ö
2meV
Double slit electron interference
Results with low intensity and high intensity electron beams
Comparison with light photons
Probabilistic interpretation of wave amplitude
9.2.7 Electron microscopes
Estimate of anode voltage needed to produce wavelengths of the order of the size of the atom
Principle of operation of the transmission electron microscope (T.E.M.)
Limitations of the theoretical resolving power due to lens aberration and sample thickness
Comparison of the de Broglie wavelength of electrons at thermal energies with electrons at energies of the order of keV
An example question on the photoelectric effect and wave particle
duality
Model answers for this question
Principle of operation of the scanning tunnelling microscope (S.T.M.)
Homework Answers
Mark scheme for homework Q on STM
acknowledgement:
notes courtesy of R. Bocking
