| The Following Topics Might Appear on Quiz 4 (2020) |
| Inertial reference frame: frame of reference of an observer traveling with a constant velocity. |
| Principle of Relativity: The laws of physics are the same in all inertial reference frames. |
| "Light travels at 3 x 108 m/s" is a law of physics. [So c is the same for all observers.] |
| Time dilation [Moving clocks slow down.] |
| Gravitaional Time dilation [Clocks slow down in gravity wells.] |
| Length contraction [Moving meter sticks shorten.] |
| Simultaneity is not absolute. [Observers traveling at different speeds will not agree on which events happened at the same time.] |
| Observers moving with the clock or meter stick notice no time dilation or length contraction. |
| Time dilation and length contraction factor γ = (1 - v2/c2)-½ > 1 |
| Gravitational time dilation factor γ = (1 -2GM/(c2r))-½ > 1 |
| Time dilation: multiply by γ to get increased tick time of moving (slowed down) clock. |
| Length contraction: divide by γ to get decreased length of moving (shortened) meter stick. |
| Equivalence of mass and energy (E = mc2) |
| Photoelectric Effect (energy of ejected e- depends on frequency of light not its intensity) |
| Energy of photon (E = hf) |
| Frequency of photon an e- emits or absorbs in changing its energy level in an atom [f = (Ef - Ei)/h] |
| Key assumptions of Bohr atom: 2πr = nλ, λ = h/p |
| Dependence of Bohr atom's energy levels on n (En ~ -n-2) |
| Definition of coherent radiation (same phase, same frequency, same direction) |
| Stimulated Emission (photon of right frequency is "cloned" when it hits an excited atom ==> Laser light) |
| Compton Scattering Formula (X-rays act like particles with momentum p = h/λ. Wavelength of scattered X-ray depends on scattering angle) |
| De Broglie Wavelength of a particle (λ = h/p) |
| Quantum theory required to describe system when De Broglie wavelength of its particles ≥ size of system |
| Davisson-Germer Experiment (electrons act like waves in scattering from lattice according to Bragg's law) |
| Wave-particle duality (particles can act like waves, waves like particles) |
| Heisenberg Uncertainty Principle: For any particle, (uncertainty in position) X (uncertainty in momentum) ≥ h/(4π) |
| Schrodinger Equation (solutions explain atomic structure, energy levels) |
| Quantum numbers for electron in an atom [n (principal), l (angular momentum), ml (magnetic), s (spin)] |
| Possible values for quantum numbers 1 ≤ n < infinity 0 ≤ l ≤ (n-1) -l ≤ ml ≤ l s = ±1/2) [Caution: l = "el", 1 = "one"] |
| Pauli Exclusion Principle (two electons cannot have the same set of values for their quantum numbers) |
| Central Field Approximation (allows simple analysis of hydrogen atom to be applied to complex atoms) |
| Labels of subshells (l=0 → s, l=1 → p, l=2 → d, etc.) |
| Number of orbitals in a subshell = 2l + 1 = number of values of ml[Note: s, p, d, etc. are subshells. px, py, pz are orbitals of the p subshell.] |
| Max occupancy of a subshell = 2(2l + 1) = 2 x (number of orbitals) |
| Max occupancy of a shell = 2n2 |
| Electron has a magnetic moment (i.e. it's a tiny magnet due its spin) |
| Zeeman Effect: Energy level splitting due external magnetic field. [The stronger this field, the stronger the splitting] |
| Spin-Orbit Effect: Slight energy level splitting due to the magnetic field produced by the motion of the nucleus (from the electron's point of view) |
| Quiz will be: |
| Multiple Choice and T/F |
| concepts and calculations |
| online |
| time limited |