Untitled

Slide 1

• The photoelectric effect
• Shows that light can behave as a particle and as a wave.
• Can only be explained in regards to light being a particle or quanta of energy.
• Work function is the minimum energy required to release an electron from the surface of a metal, varies depending on the metal.
• [Therefore the threshold frequency is dependent on the type of metal used.]
• Threshold frequency is the minimum frequency for an electron to overcome the work function.
• THERE IS NO PHOTOELECTRIC EMISSION of electrons from the surface of a metal if the frequency is below the TF.
• This is because the energy of a photon is dependent on its frequency. E=hf
• Below the threshold frequency, the PHOTON DOES NOT have enough energy to LIBERATE THE ELECTRON from the surface of the metal.

Slide 2

• According to C=FLambda, wavelength of light must be below a max value.
• The MAXIMUM KE of electrons increases as the frequency increases, not affected by intensity.
• As the intensity increases, number of photons increases, so do the number of electrons emitted, proportional
• Electrons absorb 1 photon at a time: 1:1 interaction
• Frequency affects the electron ENERGY, intensity affects the NUMBER of electrons emitted.
• No time delay unlike predicted:
• Light travels as photons,
• which carry energy in discrete packets,
• with a 1:1 interaction
• Emitted electrons have a range of kinetic energies up to a maximum because:
• Energy of photons in fixed
• 1:1 interaction between photon and electron
• Energy=required for electron to escape from the metal surface
• Electron needs to overcome the work function