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Take out hwk & tables. Compare answers to hwk sets. List 2 pieces of evidence that light is a wave. Diffraction Interference. List 1 piece of evidence that light is a stream of particles. Photoelectric effect. List 1 piece of evidence for the Bohr model of the atom. - PowerPoint PPT Presentation
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Take out hwk & tables.
Compare answers to hwk sets.
List 2 pieces of evidence that light is a wave.
• Diffraction• Interference.
List 1 piece of evidence that light is a stream of particles.
• Photoelectric effect
List 1 piece of evidence for the Bohr model of the atom.
• Emission or Absorption spectra
Ref Table Page 3.
Standard Model
• Physicists have developed a theory called “The Standard Model” . It explains what matter and energy are, what holds matter together, and how forces are communicated.
Standard Model• It was once thought that the fundamental particles were
electrons, protons, neutrons.
• Now more & smaller subatomic particles
found – quarks & in the nucleus.
• Forces are carried by particles too!
Antimatter particles
• Same mass but opposite charge & spin.
• When a particle meets its antiparticle twin, they completely annihilate, destroy.
All matter classified Hadrons or Leptons Hadrons made from quarks.
p+ & no
Quarks can’t exist alone.
Protons, Neutrons: are baryons made of only up & down quarks.
• Ex 1. How many up & down quarks in a p+?
• Charge = +1
• Baryons have 3 quarks only.
• 2 up & 1 down.
• u + u + d
• +2/3 +2/3 – 1/3 = +1
• Ex 2: How many up & down quarks in a no?
• Charge = 0
• 1 up & 2 down.
• u d d
• +2/3 -1/3 -1/3 = 0
The Atom
Leptons
• The most familiar member of this group is the electron e, but there are also heavier particles called the muon and the tau .
• For each of those, there is a smaller “partner” called a neutrino .
• The leptons are all capable of independent existence.
All particles have anti-particles same mass.• Antiparticles behave same as corresponding matter particles, except
they have opposite charges.
• A proton is electrically positive - an antiproton is negative.
• Gravity affects matter and antimatter the same way.
• If matter & corresponding antimatter meet,
they annihilate into pure energy!
Antimatter Notation add bar to antimatter: Mesons quark & antiquark.
3. A particle is composed of 2 charm, & 1 bottom quark.
What is its charge? • +1.
• What type of particle is it?• Write the symbols & charges for all the particles.
• c c b• +2/3 +2/3 -1/3
4. A particle is composed of 1 anti-strange, & 1 down quark.
• What type of particle is it? • Meson.
What is it’s charge? • 0.
• Write the symbols & charges for all the particles.
• s d
• +1/3 -1/3
All stable particles must have whole number of elementary charge!
• Quarks cannot exist by themselves.
• No stable particle can have + 1 1/3 charge but can have
• +2, -1 etc.
Forces & Force Exchange Particles4 Fundamental Forces
• Strong Nuclear (Nuclear)• Electromagnetic• Weak (Nuclear)• Gravity
The universe exists because the fundamental particles interact. These interactions include 4 attractive & repulsive forces, decay, & annihilation.Force particles are gauge bosons.
Strong Force
• Short Range, Attractive only – holds nuclear particles together.
• Particle = gluons.
Electromagnetic Force
• Long range. Attracts & repels charged particles (Coulomb’s Law).
• Carrier particle = photon.
Weak Force
• In the nucleus. Involved with decay of particles. Short range.
The carrier particles of the weak interactions are the W and Z bosons.
Gravity
• Long range weakest force. Attractive only.
• The gravity force carrier particle has not been found. It, however, is predicted to exist and may someday be found: the graviton.
Quarks & Leptons 5:40 min.http://www.youtube.com/watch?
v=aTFCKbZw8QYHwk:
1.Read Text 25-4 pg 917-923
Do pg 923 #1,2 Pg 928 #30 – 37 Full sentences!
2. Bring back textbook!
Summary:• EM energy can be thought of as tiny particles
(photons) related to f.
• E in EM radiation/photons E = hf.
• Matter has E stored in nucleus.
• E in matter E = mc2. Joules.
• 1 u = 1 p+, 1no, = 931 MeV.
The charge on the quark below would be:
• +1
• -1
• +2/3
• -2/3
This particle is a:
a. Lepton
b. Proton
c. Meson
a. neutron
Cern Standard Modelhttp://www.youtube.com/watch?
v=V0KjXsGRvoA&feature=related5 minutes
Comprehensive Standard Model Summery(15 minutes)Cassiopeia
http://www.youtube.com/watch?v=K6i-qE8AigE
Quantum Song
• http://www.youtube.com/watch?feature=player_detailpage&v=DZGINaRUEkU
• What is Higgs Boson 3:30
• http://www.youtube.com/watch?v=RIg1Vh7uPyw
• What now for the Higgs 8:00 min w/ad.
• http://www.youtube.com/watch?v=649iUqrOKuE
Regents Problems Wksht.