Quantum physics (C13) Flashcards
What ideas did the photoelectric effect challenge?
That EM radiation was waves
What does wave theory predict about the transfer of energy?
That overtime waves will transfer more and more energy to a surface
What is an electroscope?
Device which can have a charge induced and then displaces that by a gold leaf rising (due to the repulsion of the charges)
Four observations from the photoelectric effect?
- Intensity doesn’t affect emission of photoelectrons
- Above threshold frequency the emssion is instantaneous
- Above f0 intensity determines number emmitted and frequency controls their KE
- It is easier to remove electrons on certain metals
What model is used to solve the photoelectric effect?
Photons (by einstein)
describe the emission of a photoelectron
1:1 interaction
must be above f0
speed is determined by left over frequency
What is the work function of a metal
The minimum energy required to remove an electron from a specific metal (E=hf0)
What is a more apprpriate unit than joules in the quantum realm?
electron volt (1.6 x 10^-19J)
What is the range of KE energies of photoelectrons
0 –> (hf-work function)
What is the stopping voltage
It’s the value of the voltage used to stop the opposing work done by a photoelectric cell
- it is used to calculate KE max of emitted photoelectrons
What did de broglie propose
matter had wave like propeties
What experiment showed particle-wave duality
electron diffraction
How are the electrons generated in the electron gun
hot wire emits electrons and then p.d. accelerates them
What is used as the diffraction grating for electrons?
graphite crystal
What is wave-particle duality?
Quantum phenomenon - all particles can display wave-like propeties and vice versa
