Physics 4 – April 27, 2017 P3 Challenge –

Slides:



Advertisements
Similar presentations
Wave-Particle Duality
Advertisements

Lecture Outline Chapter 30 Physics, 4th Edition James S. Walker
Knight - Chapter 28 (Grasshopper Book) Quantum Physics.
Cutnell/Johnson Physics 7th edition
Ch 9 pages ; Lecture 20 – Particle and Waves.
The Modern Atomic Model After Thomson: Bohr, Placnk, Einstein, Heisenberg, and Schrödinger.
Modern Physics Lecture III. The Quantum Hypothesis In this lecture we examine the evidence for “light quanta” and the implications of their existence.
AP Physics Chapter 28 Quantum Mechanics and Atomic Physics
6. Atomic and Nuclear Physics Chapter 6.4 Interactions of matter with energy.
Atoms: Not to Be Cut. Dalton’s Theory He deduced that all elements are composed of atoms. He deduced that all elements are composed of atoms. Atoms are.
The de Broglie Wavelength Lesson 11. Review Remember that it has been proven that waves can occasionally act as particles. (ie: photons are particles.
Chapter 27 Quantum Theory
PHY 102: Quantum Physics Topic 3 De Broglie Waves.
Electromagnetic Radiation
Review. The Wave Nature of Light Important: When a light wave travels from one medium to another, its frequency does not change, but its wavelength does.
Pre-IB/Pre-AP CHEMISTRY
Quantum Theory of Light A TimeLine. Light as an EM Wave.
Light: oscillating electric and magnetic fields - electromagnetic (EM) radiation - travelling wave Characterize a wave by its wavelength,, or frequency,
The Photoelectric Effect
Quantum Physics. Black Body Radiation Intensity of blackbody radiation Classical Rayleigh-Jeans law for radiation emission Planck’s expression h =
Chapter 71 Atomic Structure Chapter 7. 2 Electromagnetic Radiation -Visible light is a small portion of the electromagnetic spectrum.
Classical ConceptsEquations Newton’s Law Kinetic Energy Momentum Momentum and Energy Speed of light Velocity of a wave Angular Frequency Einstein’s Mass-Energy.
Wave Nature of Matter Light/photons have both wave & particle behaviors. Waves – diffraction & interference, Polarization. Acts like Particles – photoelectric.
G. Energy of a photon You should be able to: describe the particulate nature (photon model) of electromagnetic radiation state that a photon is a quantum.
Quantum Physics Study Questions PHYS 252 Dr. Varriano.
Enduring Understanding 1.D: Classical mechanics cannot describe all properties of objects.
By: Conor Donohue and Jen Davis. Waves are everywhere. But what makes a wave a wave? What characteristics, properties, or behaviors are shared by all.
Metal e-e- e-e- e-e- e-e- e-e- e+e+. Consider a nearly enclosed container at uniform temperature: Light gets produced in hot interior Bounces around randomly.
1 My Chapter 28 Lecture. 2 Chapter 28: Quantum Physics Wave-Particle Duality Matter Waves The Electron Microscope The Heisenberg Uncertainty Principle.
WAVE +PARTICLE =WAVICLES. The Phenomenon explaining particle nature of light.
Physics 1C Lecture 28B Compton effect: photons behave like particles when colliding with electrons. Electrons and particles in general can behave like.
Electromagnetic Spectrum Light as a Wave - Recap Light exhibits several wavelike properties including Refraction Refraction: Light bends upon passing.
Atomic Particles  Atoms are made of protons, neutrons and electrons  % of the atom is empty space  Electrons have locations described.
Chapter 29 Particles and Waves.
Quantum Mechanics. Planck’s Law A blackbody is a hypothetical body which absorbs radiation perfectly for every wave length. The radiation law of Rayleigh-Jeans.
Quantum Theory of Light.
As an object gets hot, it gives Off energy in the form of Electromagnetic radiation.
Quantum Physics. Quantum Theory Max Planck, examining heat radiation (ir light) proposes energy is quantized, or occurring in discrete small packets with.
Leading up to the Quantum Theory.  exhibits wavelike behavior  moves at a speed 3.8 × 10 8 m/s in a vacuum  there are measureable properties of light.
Quanta to Quarks Focus Area 2. Wait…Electrons are waves? In explaining the photoelectric effect, Einstein introduced a model of electromagnetic radiation.
DUALITY PARTICLE WAVE PARTICLE DUALITY WAVE © John Parkinson.
Quantum Theory & the History of Light
Questions From Reading Activity? Assessment Statements  Topic 13.1, Quantum Physics: The Quantum Nature of Radiation Describe the photoelectric.
Wave Particle Duality Quantum Physics Lesson 3 Today’s Objectives Explain what is meant by wave-particle duality. Explain what is meant by wave-particle.
Modern Physics 2. Dalton’s Atomic Theory 5 points 1)Elements are made of atoms 2)All atoms of an element are identical. 3)The atoms of different elements.
Topic I: Quantum theory Chapter 7 Introduction to Quantum Theory.
Chemistry I Chapter 4 Arrangement of Electrons. Electromagnetic Radiation Energy that exhibits wavelike behavior and travels through space Moves at the.
Quantum Mechanics and Atomic Physics
Quantum Theory Chapter 27.
Quantum Physics Lesson 6
Finish up the photoelectric effect
Atomic Models Scientist studying the atom quickly determined that protons and neutrons are found in the nucleus of an atom. The location and arrangement.
Electromagnetic Radiation
Chapter 6 Electronic Structure of Atoms
Introduction to Quantum Theory for General Chemistry
Physics 3 – Sept 30, 2016 Do Now: P3 Challenge –
Matter Waves Louis de Broglie
Tools of the Laboratory
Bohr’s Third Postulate
Devil physics The baddest class on campus IB Physics
The de Broglie Wavelength
Matter Waves Louis de Broglie
Chapter 27 Early Quantum Theory
Conceptual Physics 11th Edition
Light and Energy Electromagnetic Radiation is a form of energy that is created through the interaction of electrical and magnetic fields. It displays wave-like.
6.1.1 Photons, Photoelectric Effect, and Particle Nature of Light
Compton Effect de Broglie Wavelengths
Quantum Mechanics.
Wave Nature of Matter Just as light sometimes behaves as a particle, matter sometimes behaves like a wave. The wavelength of a particle of matter is: This.
Physics 4 – April 12, 2019 Do Now – Hand in the PhET acivity, Check out these links =PLX2gX-ftPVXVfoaIeiZcVZcHyeSpdkHKo.
Presentation transcript:

Physics 4 – April 27, 2017 P3 Challenge – Show how the quark composition for a neutron predicts no charge.

Objectives/Agenda/Assignment 12.1 Matter and Light Assignment: p502 #1-23 Agenda: Wave/particle duality Momentum of light Photoelectric effect Matter waves Electron diffraction

Wave particle duality Matter Particles Waves Light Atoms Stoichiometry Lots of experiments!!! Double slit experiment works for beams of electrons!!! Photoelectric effect – Light on metal ejects electrons depending on frequency, not intensity Electromagnetic Radiation Ray diagrams, Reflection, refraction, mirrors, lenses Double Slit Expt – Proves waves

Photoelectric Effect Wave Model predictions: The intensity of the radiation should have a proportional relationship with the resulting kinetic energy. The photoelectric effect should occur for any light, regardless of frequency or wavelength. There should be a delay on the order of seconds between the radiation’s contact with the metal and the initial release of photoelectrons. (time for energy to build up) http://phet.colorado.edu/en/simulation/photoelectric

Photoelectric Effect Experimental result: The intensity of the light source had no effect on the kinetic energy of the photoelectrons. Kinetic energy of the photoelectrons depends on the frequency of light used. Below a certain frequency, the photoelectric effect does not occur at all. There is no significant delay (less than 10-9 s) between the light source activation and the emission of the first photoelectrons.

Photoelectric effect hf =  + Ek The energy of the photon of light must be equal to the work function, , of the metal. Any excess energy results in the form of kinetic energy of the electron that is ejected from the metal. E is measured with the stopping voltage for a given metal and frequency. Ek is then eV, the charge on an e times the stopping voltage.

Momentum of light Even though photons has no mass, they nevertheless have momentum. Some observable evidence of this is the momentum that is delivered to a space sail from “solar wind”. Solar wind is light. But that light can collide with a sail and deliver some momentum, even though light is massless. Special relativity provides some insight: E2 = p2c2 + m2c4 For a massless particle, this is E = pc. p = E/c = hf/c (c=f so 1/ =f/c) p=h/  The momentum of light depends on the wavelength of light.

The Wave Nature of Matter Louis de Broglie posited that if light can have particle properties, matter should exhibit wave properties. http://www.youtube.com/watch?v=DfPepr Q7oGc Dr. Quantum De Broglie proposed that the relationship between mass and wavelength was p = h mv

Matter waves DeBroglie proposed that particles have a wave nature and a corresponding wavelength given by 𝝀= 𝒉 𝒑 = 𝒉 𝒎𝒗 Echoes the momentum of light: p=h/ Davisson-Germer found that beams of electrons diffract producing an interference pattern with 𝐧𝝀=𝒅𝒔𝒊𝒏𝜽 The wavelength observed in the diffraction experiment agrees with the wavelength predicted based on the mass of an electron. This confirms the theory of the wave nature of particulate matter.

Describing matter waves - QM The Bohr model of the atom with quantized levels can be explained by using quantized angular momentum. 𝒎𝒗𝒓= 𝒏𝒉 𝟐𝝅 h/2 is so common in QM that it is known as h (h-bar) This assumption leads to the observed energy levels for the hydrogen atom that were described by Rhydberg. 𝑬=− −𝟏𝟑.𝟔 𝒏 𝟐 eV Give the energy of an electron in energy level n in units of eV.

The wavefunction - orbitals The matter wave of the electron within the hydrogen atom has been completely described. This two body system can be solved. No other system (3+ particles) is able to be solved with our current level of computational ability. We assume that all other atoms have similar solutions The wavefunction exists in space-time and describes the probability of finding an electron in a given volume of space. 𝑷 𝒙,𝒕 = 𝚿(𝒙,𝒕) 𝟐 𝚫𝑽

Uncertainty principle With Newtonian mechanics, if we know the initial conditions of a physical system, we can calculate the conditions of the system at some later time. Recall all of the kinematics, dynamics and energy calculations we have done to do this. We cannot do the same with small particles, because of their wave duality. We can’t exactly know the position and momentum of a particle. There will always be a finite uncertainty, a theoretical limit to how good your measurements can be: 𝚫𝒙𝚫𝒑≥𝒉/𝟒𝝅 Also 𝚫𝑬𝚫𝒕≥𝒉/𝟒𝝅

Tunneling Consider an electron that is confined to a “box”: a region of space in the x dimension. The wavefunction for the electron will have a probability that is large within the box. But unlike a particle that’s confined to a box, a wavelike particle has a small probability that it will be located on the other side of the barrier. An important application of this phenomenon is the Scanning Tunneling Electron Microscope which is able to use an electron beam that tunnels into the surface of other atoms. In this way we can take pictures of atomic scale items.

Exit slip and homework Exit Slip – What is the wavelength associated with a proton moving at 7.3 x 106 m/s? What’s due? (homework for a homework check next class) p502 #1-23 What’s next? (What to read to prepare for the next class) Read 12.1, 12.2