Untitled

Slide 1

• PE EFFECT
• Shows that light can behave as a particle and as a wave.
• Can only be explained in regards to light acting as a particle or as a quanta of energy.
• Work function is the minimum amount of energy required to release an electron from the surface of the metal, varies depending on metal.
• [Therefore the threshold frequency is dependent on the type of metal used.]
• Threshold frequency is the minimum frequency of an electron to overcome the work function
• No photoelectric emission of electrons from a metal surface if the frequency is below the threshold frequency .
• This is because the energy of a photon is dependent on the frequency. E=hf
• This is because the photon does not have enough energy to liberate an electron from the surface of the metal.
• This is because the photon does not have enough energy to allow the electron to overcome the work function.

Slide 2

• According to c=F Lambda, the wavelength of light must be below a maximum value.
• MAX KE of electrons increases as frequency increases , unaffected by intensity.
• intensity increases- more photons- more electrons emitted- proportional.
• 1 electron absorbs 1 photon -- 1:1 interaction.
• Frequency affects electron ENERGY, intensity affects number of electrons emitted.
• There is no delay unlike predicted:
• Light travels as a photon
• Which carry energy in a discrete packets
• with a 1:1 interaction
• Emitted electrons have a range of Kinetic Energies up to a maximum because:
• Energy of photons is fixed
• 1:1 interaction between photon and electron
• Energy=required to release an electron from the surface of the metal
• Electron needs to overcome the work function.
• Max KE= Photon energy-work function
• Electrons deeper in the metal require more energy to escape from the surface of the metal so have less KE.

Slide 3