section 1 - particles and radiation. Flashcards
what is an isotope?
an atom with the same atomic number, but different nucleon number - same no. protons, different no. neutrons.
equation for specific charge?
specific charge (of a nucleus) = charge / mass.
proton: (p)
charge (C) : 1.60 x 10^-19
mass (kg) : 1.67(3) x 10^-27
neutron: (n)
charge (C) : 0
mass (kg) : 1.67(5) x 10^-27
electron: (e-)
charge (C) : -1.60 x 10^-19
mass : 9.11 x 10^-31
antimatter?
same: REST MASS + REST ENERGY.
different: CHARGE. (-> exception neutrons + neutrinos (+ antimatter))
neutrino/antineutrino: (v, v^_)
rest mass: 0
charge: 0
is the strong nuclear force attractive or repulsive?
attractive up to 0.5 fm, then repulsive.
what is the max. range of the strong nuclear force?
3-4 fm.
the theory behind strong nuclear force?
in stable atoms, atoms are neither expanding or shrinking. electrostatic repulsion between similar charged nucleons occurs. therefore there must be an attractive force that is short range.
how does alpha decay cause an nucleus to change?
NUCLEON NUMBER: -4
ATOMIC NUMBER: -2
what is the alternate name for an alpha particle?
helium nucleus.
how ionizing is alpha radiation? how penetrating is alpha radiation?
highly ionizing. lowly penetrating (paper stops)
wave speed of the electromagnetic spectrum?
3 x 10^8 m/s
electromagnetic spectrum from longest wavelength to shortest wavelength?
radio, microwaves, infrared, visible, UV, x-rays, gamma rays.
photon energy equation:
photon energy = hf (E = hf)
what is annihilation?
when a particle and its antiparticle collide and their masses are converted into energy (x2 photons).
ANNIHILATION: min. photon energy equation:
2hf (min) = 2E –> hf = E
E = rest energy.
hf = energy of one photon.
ANNIHILATION: NON-min. photon energy equation:
2hf = 2E + 2KE --> hf = E + KE hf = energy of one photon.
what is pair production?
when a photon with SUFFICIENT ENERGY creates a particle and its corresponding antiparticle, and vanishes.
PP: min. energy of photon req. equation:
hf(min) = 2E E = rest energy hf = photon energy
what is the eV –> J conversion?
1eV = 1.60 x 10^-19 J
what types of particles does the strong nuclear force act between?
hadrons - protons and neutrons –> EQUALLY.
what is the weak nuclear force?
force responsible for beta decay.
properties of weak nuclear force?
weak - doesn’t affect stable nuclei.
short range.
what types of particles does the weak nuclear force act between?
all.
what are the four fundamental forces?
1) strong nuclear force.
2) weak nuclear force.
3) gravity.
4) electromagnetic.
what is the exchange particle for electromagnetic force?
virtual photon.
what is the exchange particle for the strong nuclear force?
gluon/pion.
what is the exchange particle for the weak nuclear force?
W bosons (W+ / W- ).
describe what happens to the participants of electromagnetic repulsion?
particles of the same charge come close to each other. exchange a virtual photon. move off it opposite directions. no change to particle. (often e-)
describe what happened to the participants of beta minus decay?
NEUTRON –> PROTON.
emits a BETA MINUS particle (e-) + ELECTRON ANTINEUTRINO.
during beta minus decay, how does the quark composition of the nucleons involved change?
DOWN quark to UP quark.