Particle Physics

isotope

same proton diff neutron

strong nuclear force (snf)

counteract electrostatic repulsion and acts on neutrons in small range

unstable

too many p n pn

alpha decay

too many p n

beta minus

too many n → proton electron antineutrino

neutrinos

conserve momentum

antiparticle

same rest energy and mass diff everything else

photon

packets of em radiation that transfer energy but no mass

annihilation

particle antiparticle collide releasing 2 photons in opposite directions

use of annihilation

pet scans release positron in body detect gamma photons

pair production

photon converted into matter and antimatter if ephoton > rest ebothparticles

exchange particles

carry energy and momentum between force experiencing particles

weak force

wbosons 3×10-18 all particles

weak force

wbosons 3×10-18 all particles

electromagnetic

virtual photons infinite charged particles

weak nuclear force (wnf) interactions

beta decay electron capture proton electron collision

electron capture

when particle has too many p p + inner electron → neutron and neutrino

Beta plus decay

proton → neutron + positron + neutrino

beta plus decay

proton → neutron + positron + neutrino

beta minus decay

neutron → proton +electron +anti neutrino

photoelectric effect

photoelectrons emitted from a metals surface after a light above a certain frequency is shone onto it

what does photoelectric effect prove

light is a particle

working function

min energy for electron to be emitted from metal surface

stopping potential

pd to apply across metal to stop photoelectrons with ekmax

what is the use of stopping potential

find ekmax of released photoelectrons

excitation

electrons move up a discrete energy level after gaining energy

ionisation

the electron is removed from the atom if eelectron>eionisation

after excitation

electron returns to original level and energy is released as a photon if e = energy level difference

flourescent tube

low pressure mercury vapour → electron collide with atoms →excite mercury atoms→ dexcite uv photons→ excite tube coating →dexcite releasing visible light photons

1eV

energy gained by 1 electron when passed through a pd of 1V

line spectrum

after light through diffraction grating each line diff wavelength of light

line absorption spectrum

continuous spectrum with black lines at wavelengths

light as particle

photoelectric effect

light as wave

diffraction

momentum changes

changes amount of diffraction

leptons

fundemental dont experice snf

hadrons

made of quarks

baryons

3 quarks

quark composition of protons

uud

quark composition of neutrons

udd

mesons

quark antiquark pair

proton

only stable baryon

strange particles

produced by snf decay by wnf