Key Concepts of Modern Physics in the Physics 30 Curriculum

correlatedwith the Pearson Text

Physics

- quick overview of appletscorrelated with these concepts

Chapter 14: The wave-particle duality reminds us that sometimes truth really is stranger than fiction!

– The quantum:» The Photoelectric Effect

» The Compton Effect

» The Wave-Particle Duality

Chapter 15: Electric force and energy quantization determine atomic structure

– Quantization and Structure:» The discovery of the electron

» Quantization of charge

» The discovery of the nucleus

» Interaction of photons and matter

» The Bohr model

Chapter 16: Nuclear reactions are among the most powerful energy sources in nature

– The Nucleus» Binding energy

» Nuclear stability – nuclear decay

» Nuclear energy

Chapter 17: The development of models of the structure of matter is ongoing

– The “Deep Structure” of matter:

» The cloud chamber

» Particle accelerators

» The Standard model

About the Applets…

• Most are Flash-based (several are JAVA)• Most have an exploratory structure• All can be used as demo, many as

extended lab/exercises with a consistent “look-and-feel”

• Applets can be downloaded and help, assumptions, lessons customized to your needs

Chapter 14: The wave-particle duality reminds us that sometimes truth really is stranger than fiction!

– The quantum:» The Photoelectric Effect

» The Compton Effect

» The Wave-Particle Duality

The Photoelectric Effect • A curious twist – discovery of the photoelectric effect occurred

in Hertz’s confirmation of the one of the greatest achievements of classical physics

• Lenard (1902) and Millikan (1916) refined and extended the analysis of the PE

• Thomson’s discovery of the electron emerged from a common source

• A great irony – Millikan’s adamant doubt of Einstein’s quantum of light hypothesis was silenced by his own experimental genius!

Who is responsible for the idea of quantization of light

On a Heuristic Viewpoint Concerning the Production and Transformation of Light (1905)

The Photoelectric Effect

• What was “non-classical” about it?– Curious relation between photoemission,

frequency and intensity– Emission rates “all wrong!”

• Cut-off frequency and Work Functions

• Experimental evidence for the quantum hypothesis

Compton Effect

• The unequivocal “proof” for many physicists

• Could be used to demonstratenature of science and role of evidence

The Wave-Particle Duality

• Introduces the heart of quantum physics

• One of the most abstractand challenging concepts

• Introduces indeterminacy and probabilistic ideas

• Feynman’s “sum over allhistories” approach offersintriguing pedagogical possibilities

Sum over all histories –(a digression)• How a photon goes from A B in the

quantum world

The Double-Slit “Paradox”

Chapter 15: Electric force and energy quantization determine atomic structure

– Quantization and Structure:» The discovery of the electron

» Quantization of charge

» The discovery of the nucleus

» Interaction of photons and matter

» The Bohr model

Discovery of the Electron

• The “first” subatomic particle

• Critical step in understanding atomic structure

• Applet can be used in demo/exercise/lab mode

• One of the great experiments of the late 19th century

The Bohr Model

• A semi-classical model• No orbits! A good point

at which to discuss models in science

• A simple and relatively successful model for Hydrogen and Hydrogenic atoms

• Extension to angular terms or more complex atoms not plausible

(JAVA applet)

Those who are not shocked when they first come across quantum mechanics

cannot possibly have understood it.

Chapter 16: Nuclear reactions are among the most powerful energy sources in nature

– The Nucleus» Binding energy

» Nuclear stability – nuclear decay

» Nuclear energy

Binding Energy • Von Weizacker’s

Semi-empirical Formula

Strong interactionterm “bonding”= 15.56 MeV Surface area correction

term = 17.23 MeV

Coulomb repulsionterm = 0.697 MeV

Asymmetry term= 23.285 MeV

protons neutrons

Chapter 17: The development of models of the structure of matter is ongoing

– The “Deep Structure” of matter:

» The cloud chamber

» Particle accelerators

» The Standard model

The Cloud Chamber

• The “telescope” of particle physics

• Pre-requisite knowledge:– hand rules and magnetic interaction

Charged particle – magnetic field interaction

Hand rules and motionof charged particlesin magnetic fields