Optical Phenomena and Properties of Materials

Photo-electric effect

• Describe the photoelectric effect as the process whereby electrons are ejected from a metal surface when light of suitable frequency is incident on that surface.
• State the significance of the photoelectric effect.
• Define threshold frequency, f_o , as the minimum frequency of light needed to emit electrons from a certain metal surface.
• Define work function, W_o , as the minimum energy that an electron in the metal needs to be emitted from the metal surface.
• Perform calculations using the photoelectric equation:
  
• Explain the effect of intensity and frequency on the photoelectric effect.

Emission and absorption spectra

• Explain the formation of atomic spectra by referring to energy transition.
• Explain the difference between atomic absorption spectra and atomic emission spectra.
  
  • An atomic absorption spectrum is formed when certain frequencies of electromagnetic radiation that passes through a medium, e.g. a cold gas, is absorbed.
  • An atomic emission spectrum is formed when certain frequencies of electromagnetic radiation are emitted due to an atom's electrons making a transition from a high-energy state to a lower energy state.