Modern Physics (PC300) Class #9: Introductory Stuff towards Quantum Mechanics

Quantum Homework Questions Photoelectric Also some from Thornton and Rex– Due Wednesday "Yeah, well I got mine first

Experimental basis for the introduction of a quantum theory. Photoelectric Effect – Almost done X-Ray Production Charge/mass of an electron Blackbody Radiation Stefan-Boltzmann law Wien’s Displacement Law Ultraviolet Catastrophe Review what we know about how gamma particles are absorbed by matter. Photoelectric effect Compton Scattering Pair Production

Photoelectric Effect + -

Photoelectric Effect: Intensity Makes Sense: more photons - more electrons

Photoelectric Effect: Frequency Maximum KE does not depend on intensity1902: Lenard Lenard - Nobel Prize

Photoelectric Effect: Work Functions (K max )

Various Work Functions Why do different metals have different work functions? 1923 Millikan - Nobel Prize

Lab – Photoelectric Effect

X Ray Production 1901 Roentgen - Nobel Prize

EM Spectrum: X-Rays (Duane-Hunt Rule)

X Ray Production

J.J.Thompson Nobel Prize

Measuring charge/mass (e/m) Electron beam Cathode Ray Cathode Ray Tube Derive in lab

Lab ? - e/m setup

Robert Millikan Precise Measurement of e Oil Drop Experiment

Black Body Radiation “An idealized object that absorbs all the electromagnetic radiation falling on it, regardless of frequency.” Early observations – hot metals

Ultraviolet Catastrophe Classical Physics – Rayleigh-Jeans Law

Planck’s Law Unusual (Crick-Watson) type approach: -> Equation that fits data -> Make it work -> Could not justify finding 1918 Planck - Nobel Prize

Lab – Blackbody Radiation Extension - Pasco Setup