What proves the particle like nature of radiation
Example of photoelectric effect?
Gold leaf electroscope
What happens in the gold leaf electroscope experiment?
Metal and gold leaf charged by touching negative electrode from high volt supply. When UV radiation was shone onto metal plate the gold leaf fell
Observations in gold leaf experiment
- photoelectric only emitted when incident radiation was above a certain frequency
- intensity had no effect on max kinetic energy of photoelectrons
- emission of electrons was instantaneous when radiation was above the threshold frequency
What did Einstein realise from photoelectric effect?
Nature of light was a stream of photons.
Photons emitted photoelectrons in a one to one interaction
What is the work function def
The minimum energy of a photon needed to emit an electron from the surface of a metal
Value of planks constant
6.63 X 10^-34
What is an electron volt in joules
1.6 X 10^-19
What is the definition of an electron volt
The energy transferred from or to an electron when it moves through a potential difference of 1 volt
What shows wave particle duality?
Electron diffraction in electron gun
How is electron diffraction shown
Electrons emitted from a hot wire and accelerated by a potential difference. The electrons pass through a thin layer of polycrystalline graphite and diffract to show an interference pattern. As wavelength of electron is approximately the separation of carbon atoms
What did de Broglie realise and what is his equation
Wavelength is inversely proportional to its momentum
Wavelength = h/momentum
Why do emitted electrons have a maximum kinetic energy
Electrons are different depths into the metal surface, those closest to the surface need less energy to be released so have more energy to go into speed so have the maximum kinetic energy