Overview of Unit 1
- Created by: geeraf97
- Created on: 18-12-14 09:28
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- Unit 1- Particles and Quantum Phenomena
- Matter and Radiation
- Specific Charge = charge/mass
- Beta Radiation
- Atomic/proton number increases by 1
- Neutron number remains the same
- Electromagnetic waves made up of an electric and magnetic field
- Anti-Matter
- Every particle has an anti particle
- When these particles meet they annihilate themselves
- Pair production is caused by a high energy photon
- W Bosons
- Exchange particles with non zero rest mass
- Have very short ranges
- Isotopes
- Atom with the same number of protons but different number of neutrons
- A isoptope nucleus is called a nuclide
- Interactions
- Exchange particles are the action of a force
- Beta+ decay is a proton changing into a neutron, neutrino and positron
- Quarks and Leptons
- Hadrons
- Baryons: Protons, neutrons and antiparticles
- Mesons: Kaons and Pions
- Interact through the strong force and decay through the weak force
- Leptons
- Electrons, muons, neutrinos and their antiparticales
- interact through the weak force
- Neutrinos do not often interact
- Lepton Rules
- Interaction between a lepton and a hadron a neutrino/anti neutrino can form it's corresponding charged lepton
- The lepton number is conserved in any change
- In muon decay the muon becomes a muon neutrino
- Quarks
- Baryons consist of 3 quarks or antiquarks
- Mesons consist of a quark and an antiquark
- 3 quarks anti quarks are up, down and strange
- Strangeness is always conserved in the strong interaction
- Strangeness is not conserved in the weak interaction
- Conservation
- Energy and charge must be conserved
- Baryon and lepton number must be conserved
- Hadrons
- Quantum Phenomena
- Photo-electricity
- Electrons emitted if the photon has the threshold frequency
- Number of electrons emitted is proportional to the intensity of light
- Work function is the minimum amount of energy needed to escape the metals surface
- 1 photon to 1 electron
- Electron Collisions
- Ionisation is the removal of an electron from the outer shell of an atom
- Electrons excite other electrons and cause them to move to a higher energy level
- When an electron de-excites a photon is released
- Fluorescence
- Atoms absorb UV radiation and excite, when they de-excite they emit visible photons
- Mercury emits UV photons when colliding with electrons
- UV absorbed by coating and emit visible photons
- Very little energy wasted as heat
- Wave Particle Duality
- Wave nature seen through diffraction, refraction etc.
- Particle nature through the photoelectric effect
- Photons of light pass over all energy, instantly (particle)
- Matter also has a duality. Electron has wavelength and is a particle
- de Broglies Wavelength is Planck/massx velocity
- Electrons can be diffracted like a wave
- Spectra
- Spectrum of colors caused by different wavelangths
- Discrete spectrum shows lines of different colours
- Every atom has it's own spectrum depending on it's energy levels
- Photo-electricity
- Matter and Radiation
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