Quantum

• The photoelectric effect is when photoelectrons are emitted at the surface of a metal after a photon / light with threshold frequency is shone on it.
• Threshold Frequency

  The minimum amount of frequency a photon has to have in order for photoelectrons to be emitted from the surface of a meal.
• Light (or EM waves) travel in discrete packet of energy.
• Each electron in the photoelectric effect can only absorb one photon.
• If the intensity of light is increased, more photoelectrons will be released per second
• If the frequency of light is increased more photoelectrons will be released per second.
• What happens if you increase the frequency of light in the photoelectric effect?

  More photoelectrons will be released per second
• What happens if you increase the intensity of light in the photoelectric effect?

  More photoelectrons will be released per second
• The work function is the minimum amount of energy required for photoelectrons to be emitted from the surface of a metal.
• The stopping potential is the potential difference needed to be applied across a metal to stop photoelectrons with maximum kinetic energy, from being emitted.
• Measuring the Stopping potential allows you to find the Maximum kinetic energy of the photoelectron released.
• Excitation is when electrons gain enough energy to move up energy levels.
• Ionisation is when electrons gain enough energy to be removed from an atom.
• How do fluorescent tubes produce visible light?

  1. Voltage accelerates electrons through the tube 2. Free electrons hit the mercury atoms, causing its electrons to be excited. 3. When they de-excite they release photons in the UV range. 4. Fluorescent coating (phosphorus) absorbs the UV photons, causing its electrons to be excited. 5. When they de-excite they release photons of visible light.
• What do lines on an emission spectrum show?

  Each line represents a wavelength of light emitted.
• What does an Absorption spectrum show?


  Continuous spectrum of all the wavelength of light and black lines
• Light can have both wave and particle propeties.
• Examples of light behaving as a wave is interference and diffraction.
• An example of light behaving as a particle is the photoelectric effect.
• An example of light behaving as both particle and wave is the electron diffraction.
• De Broglie wavelength equation shows how the amount of diffraction changes as a particle's momentum changes.
• According to De Broglie's wavelength equation, as momentum increases, the wavelength decreases, so the amount of diffraction decreases and rings of interference pattern are closer.
• According to De Broglie's wavelength equation, as momentum decreases, the wavelength increases, so the amount of diffraction increases and rings of interference pattern are further apart.
• What does De Broglie's equation show?

  How amount of diffraction of a particle changes with its momentum.
• Knowledge and understanding of any scientific concept changes over time as experimental evidence is gathered.
• For experimental evidence to be accepted, it has to be published and peer-reviewed by the scientific community.