Particle Physics Flashcards
How does a fluorescent tube work
High energy electrons emitted from a cathode
Electrons collide with Mercury vapour causing excitation
When electrons return to ground state they emit an ultra violet photon which is absorbed by phosphorus on the inside wall of the tube
These fluorescence resulting in the emission of visible light
What observations demonstrates the wave nature of electrons
Electron diffraction
What force to hadrons react via?
The strong force
Define the absorption spectrum
A spectrum of dark lines seen on a coloured background produced when a gas absorbs photons
Define Electron volt
The energy transferred to or from an electron when it is accelerated by a potential difference of 1V
What is the photoelectric effect?
The emission of photoelectrons from the surface of a metal when a light above a threshold frequency is incident on it
Why are 2 photons produced in annihilation?
To conserve momentum
What is a pion?
Something made up of only up and down quarks
How is energy of a photon related to the frequency of light?
E=hf
Describe beta minus decay
n-> p+ -Ve+ e-
Describe proton - anti neutrino interaction
W+ boson causes p to become n and emits e+
What is a sigma particle?
A baryon made up of 1 strange and 2 quarks that are either up or down
What happens to diffraction rings when electrons travel with greater momentum?
They get closer together
Why does Einstein use Maximum Kinetic energy?
Because some electrons need more than the threshold frequency in order to be emitted to have less energy for kinetic
Why does wave theory not explain the photoelectric effect?
Eventually they would have transferred enough energy to the electrons so they would be emitted
