| What is photoelectricity | Emmision of elcetrons upon a metal by the exposure to light waves |
| Why do emitted electrons have a range of kinetic energies up to a maximum value? | Photons have energy dependent on frequency
One-to-one interaction between photon and electron
Max KE = photon energy – work function
More energy required to remove deeper electrons
RIGHT:
Energy given to the electron is fixed and a certain energy is required to overcome the work function of the metal. One to one interaction between photons and electrons. So the maximum kinetic energy is the energy of the photon minus the work function. As deeper electrons require energy to get to the surface, they have less energy than the surface electrons |
| What causes photoelectricity | Light with a high enough frequency |
| Define the threshold frequency | The minimum frequency of incident light which can cause PHOTOelectric emission |
| State what the work function of a metal is | Minimum energy required to remove electron from metal |
| Describe how the process of representing the photoelectric effect can be seen with an electroscope? | Place a negative charge on the electroscope
Shine the short wave UV light on top
This will discharge it
Causes the gold leaf to go down |
| What is an electroscope? | Scientific instrument used to detect the presence of electric charge |
| What were the conslusions drawn on the threhold freuency providing evidence against the light wave theory? | Light above a certain frequency, no matter how weak the source, could release photoelectrons instantly, whereas light of a lower frequency no matter how intense or how long the source was applied for had no effect |
| What is quantum? | Discrete quantity of energy |
| What is a photon of light? | A photon is a desrcete packet of energy |
| What is the photoelectric equation? | Max kinetic energy of a photon = 0.5 X mv^2 = planks constant X frequency - work function |
| What is a stopping potential? | The perfect pd to counteract the current caused by the photoelectric effect |
| What observations of the photoelectric effect could not be explained by the wave theory? | E = hf
Frequency is linear with energy
Intensity is indpeendent on energy
No electrons produced below a frequency value |
| Which theory of light does NOT explain the photoelectric effect? | Wave |
| USE SENECA TO WRiTE NOTeS | S |
