Quantum Flashcards
What is the work function ?
minimum energy required to remove an electron from a metal’s surface
hf - Ek
What is the threshold frequency ?
minimum frequency of light to remove an electron from the metal’s surface
What is an isotope ?
an atom with the same number of protons but different number of neutrons
What is the specific charge ?
Charge : mass ratio
charge/mass
What is the stopping potential ?
Vs = hf/e - φ (in eV) = Ek/e
Energy required to overcome electric potential energy
What is the conversion rate between eV and J ?
1 eV = 1.6 x 10 ^ -19 J
What are 2 ways electrons can be excited ?
Absorbing a photon
A colliding electron
How does the inside of fluorescent tube work ?
- high voltage -> accelerates e-
- e- collides with e- in mercury atoms -> excites them
- photon of UV light emitted -> e- deexcites
How does the coating of a fluorescent tube work ?
- coating absorbs the UV photon
- excites e- -> e- cascades down energy levels emitting photons of visible light
What is the De Broglie wavelength ?
- the wavelength of something that does not typically have wave-like properties
- λ = h/mv
When does an electron behave as a particle + wave ?
wave : diffraction
particle : bending in a magnetic field
What is an anti particle?
- a particle with the same mass but opposite charge as it’s counterpart
What is the equation for energy of an annihilation photon ?
1/2 (2 x rest energy + Ek of particle + Ek of antiparticle)
What is annihilation ?
When a particle meets its antiparticle, they convert mass and kinetic energy into pure energy
What is pair production ?
A photon of sufficient energy can change into a particle and antiparticle
What is the equation for pair production ?
2 (Rest energy of particle + Ek of particle)
What makes hadrons different from Leptons ?
Hadrons interact through the strong force
What makes baryons and mesons different from each other ?
Baryons are made from 3 quarks
Mesons are made from a quark and an antiquark
Which meson has strangeness ?
Kaons
What is the structure for proton and antiproton ?
p : udu
_ _ _ _
p : udu
what is the structure for neutron and antineutron?
n : dud
_ _ _ _
n : dud
what are the properties for K+, K0 and K- ?
K+ : q = 1, s = 1
K0 : q = 0, s = 1
K- : q = -1, s = -1
What is the structure for π+ π0 and π- ?
_
π+ : u d
_ _
π0 : d d / u u
_
π- : d u
What are the exchange particles for EM and weak forces ?
EM : γ photon
W : W+ / W- boson
What is the equation for Beta minus decay ?
n —> p + e- + Ve-
What is the equation for Beta plus decay ?
p —> n + e+ + Ve
What is the equation for electron capture ?
p + e- —> n + Ve
What is the equation for electron proton collision ?
e- + p —> Ve + n
What is the equation for neutron neutrino interaction ?
n + Ve —> p + e-
What is the Feynman diagram for beta+ decay ?
interacting : p
exchange : W+
altered : n, e+, Ve
What is the Feynman diagram for beta plus decay ?
interacting : p, Ve-
exchange : W+
altered paths : n, e-
what is the Feynman diagram for electron capture ?
interacting : p, e-
exchange : W+
altered : n, Ve
What is the Feynman diagram for electron-proton collisions?
interacting : e-, p
exchange : W-
altered paths : Ve, n
What is the feynman diagram for neutron-neutrino interaction ?
interacting : n, Ve
exchange : W-
altered path : p, e-
What are the fundamental forces in strength order ?
gravity
weak
EM
strong
What does the strong fundamental force do ?
Holds together quarks
what does the EM fundamental force do ?
acts on charged particles
what does the weak fundamental force do ?
decay of atoms
what does the gravity fundamental force do ?
attracts 2 objects, varies with mass
When is the strong for repulsive and attractive ?
Attractive less than 0.5fm and repulsive 0.5 - 3.0 fm
What will all free baryons eventually decay into ?
A proton
