31 outline particles, waves, and light propagation and scattering of light reflection and refraction dispersion polarization

Light can behave as wave or particle

Interference interference is evidence of the wave nature of light

Photoelectric Effect Light stimulates emission of electrons from metal.  Kmax independent of light intensity  explained by ‘photon’ concept of light.

Light Photon Smallest ‘bundle’ of electromagnetic field Carries energy and momentum

continuous hydrogen helium barium mercury

Electron energy transitions leading to Line Spectra Example:

elastic scattering spontaneous emission Photoelectric effect Stokes Raman scattering Anti-Stokes Raman scattering stimulated emission Compton scattering Resonance absorption

Huygen’s Principle each part of a wave at some instant is a ‘source’ point of waves the wave at a later instant is the tangential envelope of the point-sources

Fermat’s Principle Light speed in materials is v = c/n. In glass v is about c/1.5 A B

Actual light path from A to B is the path which takes the least time.

Law of Reflection

Snell’s Law

Use Snell’s Law to find the angle of refraction.

Light reflects and refracts at material boundaries.

Total Internal Reflection

Calculate critical angle if index of water is 1.33.

Mirages index of refraction of air depends on density of air

Light Dispersion Color separation in material with wavelength dependent index of refraction

Polarization of light by reflection

End