Chapter 1 - Matter and radiation Flashcards
Define the term strong nuclear force
The attractive force between nucleons that holds together the nucleus
Define the term isotopes
Atoms with the same number of protons but varying numbers of neutrons
Using the formula f=c/lambda what do each of the symbols stand for including units
F: frequency, Hz
c: speed of light in a vacuum, m/s, 3*10^8
lambda: wavelength, m
What is the formula for specific charge?
specific charge = charge/mass or Q\m
What is the overall charge of an atom?
0, they’re neutral
What is specific charge measured in?
C/kg
define the term electromagnetic wave
A wave consisting of a magnetic and electric wave travelling at right angles
They are in phase
Define the term laser power
A beam of light photons of the same frequency
When is an EM wave emitted?
When a charged particle loses energy
When an electron stops/changes direction/ slows down (in bursts-photons)
Define the term antimatter
matter which consists of elementary particles which are exactly opposite to its normal counterpart
What is the formula relating energy and frequency?
E=hf
What is the formula for beam power?
Beam power = nhf, where is n is the number of photons
What is Diracs theory?
When a particle and its corresponding antiparticle meet thy destroy each-other in a process known as annihilation converting their total mass into 2 photons
What is the opposite of annihilation?
Pair production
What is pair production?
When a photon with sufficient energy can covert into a particle and antiparticle pair which then separate
How much energy does the photon need in pair production?
Twice the amount
What is the weak nuclear force responsible for?
converting protons to neutrons or neutrons to protons
Whats the minimum amount of energy produced in annihilation?
The rest energy of that particle
What needs to be conserved in a reaction?
momentum, strangeness, charge, energy
What is the difference between photons and W bosons
W bosons have a non-zero rest mass,very short range and are charged
When 2 protons interact what is released?
A virtual photon which repel the 2
What is released when a neutron decays?
proton, W- boson –> B- and an antineutrino
What does a proton turn into in a proton rich nucleus?
neutron, W+ boson –> B+ and neutrino
What happens in a neutron neutrino interaction?
neutron –> proton, W- boson –> B-
What must you include in a Feynman diagram?
Arrows
Particles
Transfer particle (with charge)
What happens in a proton antineutrino interaction?
proton –> neutron, W+ boson –> B+
What happens in electron capture? In a proton rich nucleus?
a proton and electron interact and the proton –> neutron, W+ boson
–> neutrino
What formula(s) do you need to use to calculate the energy of a photon when only given wavelength?
f=c/lambda and E=hf
