particles and radiation Flashcards
what mediate electromagnetic force
virtual particles/ photon
carrier of weak nuclear force
w and z bosons
carrier of strong nuclear force
gluon/ pion
what is the range of the strong nuclear force
3fm / 3x10-15m
speed of light
3x10^8 m/s
what is conserved in pair production
energy
momentum
charge
lepton number
baryon number
give equations for annihilation
2mc^2=2hfmin
what happens in annihilation
a particle and its antiparticle collide
their mass is transformed into two high energy gamma photons
what is equal and opposite about the two photons created in annihilation
equal and opposite charge
through what process can gamma photon convert to an electron and positron
pair production
which constituent of the atom has the largest charge-to-mass ratio
electron
state a difference between a photon and an exchange particle of the weak nuclear force
photon rest mass=0 , w bozon rest mass >0
photon has infinite range, bosons have a finite range
whats the antiparticle of the electron
positron
what is the quark composition of k+
up
anti strange
what is the quark composition of k-
anti up
strange
what is the quark composition of k0
down
anti strange
which hadron has quark composition sss
omega
what are mesons made of
1 quark and 1 antiquark
are leptons fundamental
yes
which particle do all leptons decay to
electrons and neutrinos
whats a nuclide
type of nucleus with a set number of protons and neutrons
what is planks constant, h
6.63 x10 ^-34 J
frequency equation
f= wave speed/ wavelength
what is excitation
the process of an electron taking on exactly the right quantity of energy to move to a higher energy level
what is the ground state
the most stable energy level that an electron can exist in
what is ionisation
the process of an atom losing an orbital electron and becoming charged
what do kaons decay into
pions
what is a nucleon
a proton or neutron
what is stopping potential
the minimum potential difference required to stop the highest kinetic energy electrons from leaving the metal plate in the photoelectric effect
what are strange particles produced through and how do they decay
particles that are produced through the strong interaction
but decay through the weak interaction
what is the strong nuclear force
a force that acts between nucleons in a nucleus to keep it stable.
it is attractive at distances up to 3fm and repulsive at separations less than 0.5 fm
what is threshold frequency and what is it’s equation
the minimum frequency of photons required for photoelectrons to be emitted from the surface of a metal plate through the photoelectric effect
it is equal to the metal’s work function divided by Planck’s constant
what is work function
the minimum energy required to remove an electron from a metal’s surface
(by overcoming the metallic bond holding it in the metal)
what is the nucleon number
the sum of the number of protons and neutrons in a given nucleus
(A)
what is an energy level
defined and distinct energies at which electrons can exist in an atom. An electron cannot exist between energy levels
what is beta+ decay?
what particles are emitted?
a proton turning into a neutron
emitting a beta+ particle (positron) and a neutrino
what is beta- decay
the process of a neutron inside a nucleus turning into a proton, and emitting a beta-minus particle (an electron) and an antineutrino
are electromagnetic waves transverse or longitudinal
transverse
what phenomenon can be used to show that light behaves as a particle
the photoelectric effect
what is the photoelectric effect
when light above a particular frequency is shone on a metal, electrons are released, called photoelectrons
what equations is used to determine the energy of a photon
E = hf = hc/λ
why does a photon need to be of a minimum frequency to liberate an electron?
the energy of the photon is determined by its frequency, the photon’s energy must be greater than the work function (energy needed to break the bonds holding the electron) in order for an electron to be emitted
what happens when a photon has frequency higher than the threshold frequency
the electron will be liberated and the remaining energy is the kinetic energy of the electron
what is the effect of increasing light intensity
more photons incident on the metal each second
but as each photon carries the same amount of energy as before
it still does not contain enough energy to liberate an electron
so there will be no effect
what is he photoelectric equation
hf = ϕ +Ek(max)