Photoelectric Effect

Question 1

How does the fact that electrons are released instantaneously from the metal surface lead to the particle model of light? What would be predicted by the wave model?

Answer 1

-one electron absorbs one photon, absorbing its energy as a packet
- the energy would take time to be transferred from the light to the electron

Question 2

The kinetic energy of electrons is dependent on ______ not ____ in reality, but in if light behaved as a wave it would be dependent on ___ not ____. How does this observation lead to the particle model of light?

Answer 2

Frequency - intensity
Intensity (as intensity is related to the energy of light) frequency
- it shows the energy of a photon equals hf

Question 3

Increasing intensity of incident light increases what in reality - what should it do according to the wave model?

Answer 3

The number of electrons emitted per second (frequency of electron emission)
- should increase ENEGRY of emitted electrons

Question 4

How does increasing intensity of light leading to an increase in freqeuncy of electron emission lead to the particle model of light?

Answer 4

• intensity = power/area
  Power = energy transferred/time
  Energy transferred = number of photons x energy of one photon (hf)
  Intensity = Nhf/tA
  So intensity is directly proportional to the number of photons per second
  As one photon is absorbed by one electron this is also proportional to the number of electrons released per second