An Historical Review of Natural Phenomena and Models That Demonstrates Wave-Particle Duality

1. An Historical Review of Natural Phenomena and Models That Demonstrates Wave-Particle Duality

2. The Phenomenon Reflection and Refraction Light waves passing through one transparent medium into another are partly reflected and partly transmitted. There is a constant ratio between the angles at which the rays are hitting, reflecting, and passing.

3. The Model Reflection and Refraction Newton, ~ 1650 Light rays consist of particles that obey the laws of classical mechanics. Hugens, ~ 1650 Light rays consist of pinpoint wave sources. The direction of the wave front determines the direction of the ray.

4. The Phenomenon Circumvention Fresnel ~ 1800 Light can “circumvent” obstacles and illuminate regions that should have been shadowed (according to the laws of Geometrical Optics)

5. The Phenomenon <d> Interference Young ~ 1800 Light passing through two slits (d1mm) displays a pattern of alternating dark and light stripes on a screen placed in front of these two slits.

6. The Model Circumvention and Interference 1.Light consists of waves, which are periodic functions 2.The superposition of two waves is also a wave function 3.The light intensity is proportional to the square amplitude of the wave function sin  = m  / d

7. The Model Diffraction Grating A light ray passing through a ruled slide (d  1µ)splits into a number of rays

8. The Model   Diffraction Grating A constructive interference occurs into specific directions. The difference in optical paths for the rays coming from each slit is an integer multiple of the wavelength. d sin  = m 

9. The Phenomenon The Model Electromagnetic Radiation Hertz 1888 Maxwell 1864 An electric current alternating within a conductor produces a radio-wave propagating at the speed of light Light is an electromagnetic wave

10. The Phenomenon The Model The Photoelectric Effect Mulliken 1916 Einstein 1905 A surface of metal illuminated by light ejects electrons. The kinetic energy of the electrons is proportional to the frequency of the impinging light. Light is composed of particles whose energy is:

11. The Phenomenon The Model The Compton Effect Light is composed of particles with the following momentum: Compton 1923 A laser ray, directed opposite to the flow of a beam of hot sodium atoms, cools the atoms. This occurs due to momentum transfer from the light to the moving atoms.

12. The Phenomenon The Model Cathode Radiation Thomson 1897 The rays are composed of particles having a negative mass and charge Cathode rays are deflected off their pathway by magnetic and electric fields

13. The Phenomenon The Model The Oil Drop Experiment The charge stems from particles, of which each is charged by the elementary charge ‘e’ Mulliken 1913 Sprayed oil droplets become electrically charged by an integer multiple of a value ‘e’ charge

14. TheModel The De Broglie Wave De Broglie 1924 Particles can possess a wave-like behavior. The particles’ behavior is analogous to light when it behaves like a particle. The wavelength corresponding to a particle of mass ‘m’ and velocity ‘v’ is:

15. The Phenomenon Diffraction of Electrons from a Crystal Davison-Gremer 1927 When a beam of electrons, accelerated in a low electric field, hits a Ni crystal, it creates a diffraction pattern.

16. The Model Diffraction of Electrons from a Crystal Electrons are waves with a wavelength The three directions of the crystal create three intersecting diffraction patterns

17. The Phenomenon He 100oK He 300oK 20o15o 10o 5o 0o 5o 10o 15o 20o Diffraction of Atoms from a Crystal Stern 1930 A beam of particles (He, H2) hitting a LiF crystal splits into several rays.

18. The Phenomenon Atom Diffraction from a Crystal A supersonic beam of He particles hitting a GaAs crystal splits into numerous rays