Quantum

• Photelectric effect


  An example of waves displaying particle like behaviour.

  The photoelectric effect is the emission of photoelectrons when electromagnetic radiation is incident on a metal surface.
• Stopping potential


  The potential difference required to stop the fastest moving photoelectrons moving with maximum kinetic energy.
• Threshold frequency


  The minimum frequency of EM radiation in order for photoelectrons to be emitted.
• Increasing Intensity (photoelectric effect)

  Increasing intensity of incident EM wave will increase the number of photoelectrons emitted (since more photons of EM waves are incident). It does not increase the kinetic energy of the emitted photoelectrons. This shows that there is a one to one interaction between an electron and a photon.

  One electron can only absorb one photon.
• Excitation


  When an electron moves from a lower energy level to a higher energy level within an atom.
• De - excitation


  An excited electron will lead to an unstable atom. Therefore the excited electron will emit photons - to loose energy - and move to a lower energy level.
• Ground state


  The lowest energy level. The further an energy level is from the nucleus, the higher the energy level.
• Fluorescent lights


  Electrons are accelerated - via an applied potential difference - through a bulb which contains low density gas such as neon or mercury. Electrons collide with electrons in the gas atoms, causing these electrons to excite, emit photons and de-excite. These photons are then absorbed by electrons in the phosphor coating of the bulb. This causes excitation and de-excitation of the electrons which leads to photons of visible light being produced.
• Wave - particle duality


  The idea that particles are able to behave like waves.

  (de Broglie wavelength = h/mv)
• Electron diffraction


  An example of wave - particle duality.

  This is where electrons are able to be diffracted and produce a wave - like pattern on a screen. This is because, a particle is able to behave like a wave if it is able to able to interact with something of similar size to it's de Broglie's wavelength.
• Ionisation


  When an electron is removed/kicked out of an atom
• 1 electron volt


  1.60 x 10^-19 J
• Work function


  The minimum amount of energy required to liberate an electron from a surface (photoelectric effect).