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S207
Key terms for S207
| Term | Definition |
|---|---|
| acceptors | Impurities added to semiconductors, to make a p-type material, they have too few valence electrons for bonding so create holes in the valance band eg boron |
| adiabt | a pathway on a PVT surface the corresponds to an adiabatic change |
| adiabatic process | no heat transferred |
| allowed transition | a transition that meets the rules l +/- 1 , m +/- 1 or 0 and no restrictions for n |
| amorphous solid | a solid with short-range order only, more rigid than a fluid, not enough energy to get to a crystalline solid |
| Angular acceleration | rate of change of angular frequency |
| angular frequency | a characteristic of an oscillation system, scalar |
| angular momentum | vector product of l = rxp where r is displacement and p is linear momentum - for a particle |
| asymmetry affect | an effect the influences the properties of the nucleus (mass) due to the strong force being stronger for unlike nucleons |
| back EMF | EMF that opposes the supplied EMF in a motor - due to Lenz's Law |
| Balmer Series | visible lines due to the transitions within atomic hydrogen transitions to 2-6 give visable, higher give UV |
| Band Theory of Solids | says that electrons in solids are distributed into bands that can overlap or be separated , gives rise to properties of insulators, conductor and semiconductors |
| BCS theory | superconductivity is due to the formation of Cooper Pairs and the development of the superconducting energy gap at low temperatures |
| Bell's Theorm | any theory that exhibits both locality and realism can't reproduce the predictions of quantum mechanics |
| Bernoulli's principle | the rate of flow of an ideal fluid is at a maximum at minimum pressure |
| blackbody | an ideal absorber & emitter of EM-radiation, it's spectrum depends on it's temperature |
| Bohm's Theory | - a realist interpretation of QM, related to pilot wave theory |
| Bohr Model | central nucleus, orbited by electrons in defined orbital. Energy of orbitals is an integer multiple of h-bar. No radiation as long as electrons in orbital, Radiation from transitions |
| Bohr radius | the radius of the lowest energy orbital in hydrogen |
| Boltzman's distribution Law | for a classical gas at thermal equilibrium the probability of find a molecule in a phase cell of energy E is p=Ae^-E/kT |
| Boltzman's equation | S=klnW S is entropy W is the number of configurations in the equilibrium state |
| Born interpretation | the wave function determines the probability of finding a particle in a given region. for x - #x it modulus of WF^2* #x same for volume in 3D |
| Boltzman's principles of statistical mechanics | 1 the only allowed configurations are those with energy E 2 All configurations are equally likely |
| Second Law of Thermodynamics | entropy tends to a maximum |
| Bound Particle | A particle that is trapped in a potential well as it's total energy is less than the potential energy at every point on the boundary - tunneling can happen but v unlikely |
| boundary conditions | constraints on a wave by limiting it's end points |
| Boyles law | at constant T Proportional to 1/V |
| Carnot Cycle | 2 isothermal and 2 adiabatic processes, ideal gas, reversible |
| Carnot Engine | uses a Carnot Cycle - most efficient heat engine, converts heat to work |
| Charles law | at constant P V proportional to T |
| Coherence Length | the distance for the wavefunction to spread to form a Cooper pair - long in metallic crystals, short in alloys |
| conduction band | the lowest unfilled energy band in a solid - completely empty in an insulator |
| Conservative force | the work done is independent of the route followed - eg gravity on a fixed mass |
| Converging lens | thick in middle, convex- positive |
| Cooper Pair | two electrons with similar wave functions but opposite direction of propagation and opposite spin |
| Correspondence Principle | Classical and QM agree within the classical limit |
| Critical current density | the max current per area for a superconductor without it reverting |
| cyclotron motion | the circular motion of a charged particle at right angles to a magnetic field |
| degeneracy | more than one quantum state is associated with an energy |
| degrees of freedom | sum of the squared terms in the total energy sum |
| depletion region | at the boundary between a p-n junction the holes and electrons have recombined to leave bare donor and acceptor ions the create an electric field towards the p-side |
| diamagnetic | a material that becomes magnatized in the opposite direction - lower magnetic field |
| diverging lens | thin in middle - concave - negative |
| donors | impurity added to create n-type semiconducter. have more valence electrons than needed for bonding so they are released into the conduction band - eg arsnic |
| Drude's free electron model | free electrons in metals are treated as a classical gas with MB energy distribution. Electrons do not interact but can collide with the lattice |
| Dulong-Petit Law | all sold elements have a molar heat capacity of about 3R not true for diamond at RT, not true at low T. Only true if above einstein T |
| Einsteins postulates | 1 laws of physics are the same in all inertial frames of reference 2 the speed of light is the same in all inertial frames of reference |
| equipartition of energy theorm | for a system in equilibrium at T each degree of freedom contributes kT/2 to the average energy per molecule |
| extrinsic semiconductor | a semiconductor that has been doped |
| Faraday's Law | induced EMF is equal to the magnitude of the rate of change of magnetic flux through that surface |
| Fermi Energy | the energy of the highest occupied state in a system of fermions in thermal equilibrium - fermi occupation level = 1/2 |
| Fermi Level | the boundary between filled and unfilled states |
| Fermi Speed | the average speed of electrons near the Fermi level |
| Fist law of Thermodynamics | work done on a system depends only on the first and final energies not the route |
| Forward Bias | electric current across the p-n junction will increase the diffusion current - + at p -at n |
| Hall Effect | a magnetic field perpendicular to a thin metal will cause a pd to form |
| Heisenburg uncertainty principle | 1 limit to precision of knowledge of position and momentum product of uncertainties must be more than h-bar/2 2 limit to precision of knowledge of energy in a time limit product of uncertainties must be more than h-bar/2 |
| Hund's rule | in the ground state have maximum spin |
| Huygen's principle | each point on a wavefront can be considered a new source of waves |
| Ideal flow | constant density, no viscosity and no eddies |
| Ideal fluid | has ideal flow and incompressible |
| insulator | have an energy gap between valance band and conduction band of more then 3eV |
| intrinsic semiconductor | non doped |
| isothermal process | no change in temperature |
| Josephson Junction | two superconductors separated by a thin layer of insulator - Cooper pairs can tunnel through |
| Kepler's Laws | 1 elliptical orbit - sun as one focus, 2 the area swept out by the radius is the same in equal time periods, 2 T^2 is proportional to r^3(semimajor axis) |
| Lorentz Contraction | moving rods contract in the direction of their motino |
| many world's interprtations | there exist a large number of parallel universes for each of the possible outcomes to exist int. |
| Maxwell-Boltzmann energy distribution | the equilibrium distribution of translocational energies for molecules in a gas |
| Maxwell's Equations 1 & 2 | 1 electric flux in a closed surface is proportional to the charge inside 2 the flux due to magnetic field for a closed surface is 0 |
| Maxwell's Equations 3 & 4 | 3 (Faraday +Lenz) 4 average magnetic field along the boundary of a surface depends on current per area and the rate of change of electric field |
| occupation factor | the average number of particles occupying a given quantum state in thermal equilibrium |
| magnetic quantum number | m = 0, +/- 1, +/-2 .. to +/-l z component of the spin |
| paramagnetic | a material that is magnetized in the direction of the field - larger magnetic field |
| Pauli Pressure | the pressure from a gas of fermions as a consequence of the Pauli exclusion principle, as particles are in a higher energy state they have more KE so higher pressure |
| Pauli exclusion principle | no two electrons can occupy the same quantum state |
| population inversion | required for laser action - population maintained at higher energy so the incident transition will cause emission not absorption |
| principal quantum number | n can take any integer from 1, orbital number |
| principle of complementarity | can use incompatible terms to describe a system as long as not simultaneously - waveparticle |
| quantum gas | weakly interacting indistinguishable particles that behave based on their boson/fermion nature. Only MB if wavelength much less than distance between them |
| indistinguishable particles | eg two hydrogen atoms prevents them from being labelled seperatly |
| quasi-static process | a process tin which the state changes so slowly it is considered to be a series of equilibrium states |
| reverse bias | a voltage is applied so as to inhibit the diffusion current, + at n and - at p |
| spin quantum number | the z component of the spin for electron +/-1/2 for proton +/-1 or 0 |
| spin-orbit interaction | causes splitting of energy level sue to the magnetic moment being aligned in parallel |
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