Quantum

• Photon:

  • discrete packet of energy
  • they have no mass so travel at the speed of light

  Energy is proportional to frequency. (Gamma wave = high frequency low wavelength)

  e=hf and c=f x wavelength

  so e = hf/ wavelength
• The electron volt:

  When an electron (which is negative) travels through a positive 1 voltage. The energy gained is the electron volt

  W = QV

  1eV = 1.6 x10^-19 x 1
• Finding plancke’s constant: (1/2)

  • With an LED, different colours have different threshold voltages (min voltage for current to pass through) (depends on colour of led)
  • plot on a table threshold voltage against wavelength (get wavelength from internet)
  • then plot v against 1/ wavelength on a graph
  • The gradient = V x wavelength (from v/1/wavelength)
• Finding plancke‘s constant (2/2):

  • we know energy = hf and also that energy = hc/ wavelength
  • we also know energy = charge of electron x pd
  • so eV = hc / wavelength
  • we can rearrange this so wavelength x v (our gradient) = hc / e
  • therefore our gradient x e / c = plancke’s constant

  
• The photoelectric effect - gold leaf:

  • Golden leaf with electrons displaced across
  • When ultra violet light is shon at e-, they discharge
  • The energy releases e- from atom, and the left over energy is the photoelectron’s kinetic energy
  • 1:1 photon:energy
  • Work function = amount of energy needed to release an electron
• The photoelectric effect (Einstein)

  • His formula is hf = 0| +eK where hf = energy, 0| = work function and eK = kinetic energy
  • If eK = 0, then hf = 0| so we can say f is the threshold frequency
  • Intensity of light DOES NOT affect the photoelectric effect. It MUST meet the threshold frequency for it to occur

  
• De Broglie wavelength:

  • wavelength = h/mv
  • where m = mass and v = velocity
  • the intensity of a wave at a point = the probability of a particle being there
• I have not done electron energy levels, emission and absorption line spectra. And electron diffraction tube cause I haven’t learnt it jet