Section 1: Particles And Radiation Flashcards
Mass of electron in Kg
9.11 x10^-31
Charge of proton in Coulombs
+1.6 x10^-19
Charge of neutron in Coulombs
0
Charge of electron in Coulombs
-1.6 x10^-19
Definition of specific charge
‘Charge per unit mass’
Specific charge formula
Specific charge = charge
——–
Mass
Relative strength of gravity
6 x10-39
Relative strength of electromagnetic force
7 x10-3
Relative strength of strong force
1
Relative strength of weak force
1 x10-6
i) Range of strong and weak force in metres
ii) What happens to the force beyond that range?
i) 10^-15m and 10^-18m respectively
ii) Completely drops off, doesn’t not gradually reduce
Mass of proton or neutron in Kg
1.673 x10^-27
What forms alpha decay?
2 neutrons and 2 protons
When does alpha decay happen
When the diameter of the nucleus is greater than the range of the strong force
How is energy conserved by alpha decay?
Always emitted at the same speed which means they have the same kinetic energy, therefore energy is conserved
Name three quarks.
Up, down and strange
What is the baryon number of a quark?
+1/3
Give the quark composition of a:
a) proton
b) neutron
c) antineutron
a) uud
b) udd
c) udd (antiparticles)
What is the quark composition of a meson?
1 quark and 1 antiquark
Why can you not have quark on its own?
The energy used to remove a quark from a hadron creates a quark-antiquark pair. Quark confinement
What kind of interaction can change a quark’s character? Name and describe an interaction in which this happens.
The weak interaction. In beta minus decay, a neutron decays into a proton so a down quark changes to an up quark
What is the strangeness of a strange quark?
-1
What is an exchange particle?
A virtual particle that lets a force act between two particles in an interaction
Name two exchange particles of the weak interaction.
W+ boson and W- boson
What do straight lines on particle interaction diagrams represent?
Particles (not exchange particles)
Why would a nucleus undergo electron capture?
Because it is proton rich
What is the difference between electron capture and electron-proton collisions?
In electron capture, a proton in a nucleus captures an electron from the atom, turning into a neutron and emitting a neutrino.
In an electron-proton collision, a free electron collides with a free proton to produce a neutron and neutrino
What are the exchange particles in the fundamental forces also known as?
Gauge bosons
Which particles are affected by the strong force?
Hadrons
The electromagnetic force affects…?
Charged particles
Give the gauge boson for the electromagnetic force.
Virtual photon
In what type of interaction are strange particles produced in pairs?
Strong interaction
What special property do strange particles have?
Strange particles are always produced in pairs
In what type of interaction do strange particles decay?
The weak interaction
In what type of interaction is strangeness not conserved? By how much does the strangeness change in this reaction?
The weak interaction. Strangeness can differ in a range of 1 (-1, 0, +1)
What is always conserved in particle intervention? (3)
Charge, baryon number, lepton number. (energy, mass and momentum are also conserved)
What is a photon?
A packet of EM radiation
What equation would you use to calculate the energy of a photon from its wavelength?
E =hc/wavelength
How does an antiparticle differ from its corresponding particle?
Opposite charge
Name the electron’s antiparticle.
The positron
Describe the process of pair production.
Energy can be converted into mass and produce particles, if there is enough energy. The mass is always produced in a particle-antiparticle pair.
What is produced in the annihilation of matter and antimatter?
Two gamma ray photons
What are the two largest forces acting on the particles in a nucleus?
The electromagnetic force (between protons) and the strong force
What is the range of repulsion of the strong nuclear force?
Between 0 and 0.5fm
What is the range of attraction of the strong nuclear force?
Between 0.5 and 3fm
Why does a nucleus undergo nuclear decay?
Because the forces acting on the nucleus only have a range of a few femtometres so they struggle to keep the nuclei together making it unstable
How do the nucleon and proton number change after alpha decay?
The nucleon number goes down by 4 and the proton number goes down by 2
What particles are emitted during beta-minus decay?
An electron and an antineutrino
Describe the changes in the nucleus of an atom when it undergoes beta-minus decay.
A neutron turns into a proton so the nucleon number stays the same and the proton number increases by 1
