Particle and Waves

Student Learning Objectives
Lessons / Lecture Notes
Important Equations
Example Problems
Applets and Animations

Student Learning Objectives

• To recognize phenomena that cannot be explained by classical physics, thus motivating the need for a new theory.
• To understand the photoelectric effect experiment and its implications.
• To understand the photon model and its application to the photoelectric effect.
• To understand the photon model and its application to the Compton effect.
• To understand the evidence for matter waves and the de Broglie wavelength.
• To recognize how the uncertainty principle limits our knowledge of the states of particles.

Lessons / Lecture Notes

PY106 Notes from Boston University (algebra-based):

Introductory physics notes from University of Winnipeg (algebra-based):

HyperPhysics (calculus-based)

Important Equations

Example Problems

Problem 1
A photon with a wavelength of 250.0 nm strikes a metal surface and ejects an electron that has a kinetic energy of 1.60 eV. (a) What is the momentum of the photon? (b) What is the de Broglie wavelength of the ejected electron? (c) Assuming this electron is the most energetic possible, what is the work function of the metal? (d) What is the maximum wavelength photon that will eject an electron from the metal surface? (Solutions)

Problem 2
In a Compton scattering experiment, the incident X-rays have a wavelength of 0.3120 nm and are scattered by “free” electrons in graphite. The scattering angle is Θ = 135.0o. What is the (a) energy and  (b) momentum of the scattered photon. If instead of scattering off of electrons, the photons are scattered from a molecule such as nitrogen, would the (c) energy and (d) momentum of the scattered photon increase, decrease, or remain the same? (Solutions)

Applets and Animations
 Wave / Particle Duality Here we visualize a hydrogen atom, which consists of an electron in orbit around a proton. In one view the electron is a particle and in the other view it is a probability distribution. Blackbody Spectrum How does the blackbody spectrum of the sun compare to visible light? Learn about the blackbody spectrum of the sun, a light bulb, an oven, and the earth. Adjust the temperature to see the wavelength and intensity of the spectrum change. View the color of the peak of the spectral curve. Blackbody Radiation Spectrum The Blackbody Radiation Spectrum model shows six fixed-temperature curves between Tmin and Tmax and a red variable-temperature curve that can be adjusted using a slider. Photoelectric Effect See how light knocks electrons off a metal target, and recreate the experiment that spawned the field of quantum mechanics. Pair Production and Annihilation A simple illustration of electron-positron production and annihilation. Photon Absorption and Emission This applet illustrates the absorption and emission of photons by an atom.