| A | B |
|---|
| refraction towards normal when: | light slows down |
| diffraction | proportional to wavelength/gap |
| reflection | angle of incidence = angle of reflection |
| interference | constructive and destructive; due to superposition |
| path difference = n x wavelength | constructive interference |
| path difference = (2n - 1)/2 x wavelength | destructive interference |
| PE gain from battery of voltage V | E = qV |
| KE gain of electron from voltage V | KE = qV |
| Einstein equation for the PE effect | hf = work function + KE |
| work function | 'unbinding' energy of electrons |
| electronvolt (eV) | 1.6 x 10^-19 J |
| gradient of KE vs f graph for photoelectrons | h |
| y-intercept of KE vs f graph for photoelectrons | work function |
| reactive metals have: | low value of work function |
| unreactive metals have: | high value of work function |
| pressure formula | p = F/A |
| single photons | diffract and interefere |
| de Broglie wavelength of particle | = h/p |
| momentum of photons | = h/wavelength |
| mass of photons | 0 |
| electron orbitals | standing waves around the atom |
| atomic energy levels | only special PE values allowed |
| formula for photon energy emitted after atomic transition | E = hf |
| absorption spectra | absorb photons whose energy is equal to atomic energy level gaps |
| emission spectra | emit photons whose energy is equal to atomic energy level gaps |
| ionisation level | enough energy given to atom to totally free an electron |
| energy of a single photon | hf |
| two units for h | eV s and J s |
| de Broglie for particle | h/(2*m*KE)^0.5 |
| momentum of photon | p = E/c |
| incoherent light | photons with random phases |
| wide spectrum | continuous range of wavelengths |
| line spectrum | only specific (discrete) wavelengths |
| quantised | specific (discrete) values only |
| wave-like nature | exbitis wave effects (diffraction, interference...) |
| stopping voltage | stops most energetic photoelectrons |
| threshold frequency | = work function/h |
| higher intensity light | more photons |
| Power of a light source | =nhc/wavelength |
| in phase | will interfere constructively |
| out of phase | will interfere destructively |
| thermal motion of electrons | collisions produce light |
| qualitative | no numbers required |
| quantitative | involves numbers, calculations. |
