1.1 Matter and Radiation Flashcards
What is the unit for specific charge?
CKg-1
Which part of an atom has the highest specific charge?
The electron (high charge/small mass)
How does the strong force act on nucleons?
Between 0 and 0.5fm there is strong repulsion, between 0.5 and 3fm there is strong attraction which declines as the particles get further apart
What is an alpha particle?
A helium nucleus with 2 protons and 2 neutrons
Which nuclei emit alpha radiation?
Mostly heavy nuclei with some smaller neutron deficient nuclei
What is the equation for the total energy emitted from a laser?
E= N x hf
hf is the energy of 1 photon
N is the total number of photons emitted
What is the equation for the amount of energy transferred per second by a laser and what is it measured in?
E= n x hf, measured in Watts (energy transferred per second)
n is the number of photons transferred per second
hf is the energy of 1 photon
What equation links mass and energy?
E=mc(squared)
What 3 ways can we create antimatter?
High energy collision experiments
Interactions with cosmic rays
Radioactive decay
Name a similarity and difference between matter and antimatter
Both have the same rest mass but have an opposite charge
What are the 2 processes to create and destroy matter and antimatter?
Pair production and annihilation
Define an electron volt
The energy required to move one electron across a potential difference of one volt
How do you convert joules to electron volts?
J/1.602x10-19
How do you convert eV to joules?
eV x 1.602x10-19
When does pair production occur?
When a high energy gamma ray passes near a nucleus and the gamma ray has enough energy to produce the rest mass of 2 particles
What does pair production produce?
A particle and it’s antiparticle
What happens to the particles after they have been produced from pair production?
They spiral in opposite directions due to their charge and the nearby nucleus
What will happen to positrons produced in pair production soon after their creation?
They will annihilate with another electron and form 2 gamma rays
What happens when a particle and it’s antiparticle collide?
The mass of both particles are converted in two gamma rays (to conserve momentum)
How would you calculate the minimim frequency of a produced gamma ray from annihilation?
The rest mass of the colliding particle divided by Planck’s constant
E=hf
What are the 4 fundamental forces?
Electromagnetic force
Strong force
Weak force
Gravitational force
What are the exchange particles of these forces?
Electromagnetic - virtual photon
Weak force - W +/- boson
(Gravitational - graviton)
(Strong force - gluon)
What are the differences between the 2 exchange particles we learn?
W +/- bosons: Have a rest mass, limited range, charge
Virtual photon: No rest mass, infinite range, no charge
Why is the photon in the electromagnetic interaction ‘virtual’?
Because it travels too short a distance to be seen and never misses the other particle
