Unit 7 & 12 Flashcards
Lyman series
UV, transition to n=1
Balmer series
Visible, transition to n=2
Paschen series
IR, transition to n=3
Isotope
A version of an atom with the same number of protons but different number of neutrons
Absorption of alpha particle
Skin, paper, 5cm air
Absorption of beta
A few cms body tissue, a few mms metal , 25fm air
Absorption of gamma
A few cms lead, several ms concrete
Half-life
The time taken for half of the initial number of nuclei to decay OR for the activity to fall by half
The unified atomic mass unit
1/12th the rest mass of an unbound C12 atom in its nuclear and electronic ground state.
Nuclear binding energy
The energy required to completely separate the nucleons in an atom.
Mass defect
The difference in mass of the products and reactants of a nuclear reaction.
Hadron
A particle formed from quarks.
Baryon
A particle formed from 3 quarks.
Meson
A particle formed from 2 quarks.
Lepton
Particle from electron and neutrino family.
Boson
Force carrying particle.
The Photoelectric effect - Work Function
The minimum quantity of energy that is required to remove an electron to infinity from the surface of a given solid, usually a metal.
Decay Constant
the probability that an individual nucleus will decay in a given time interval.
Activity of Sample
the number of nuclei decaying in a second (Bq).
Quantization
Conversion of a continuous range (spectrum) of values into a finite range of discrete values.
Photon
A particle of light
Threshold frequency
the minimum frequency of radiation required in order for an electron to be emitted from the surface of the metal.
De Broglie Hypothesis
All particles have an associated wavelength given by
λ = h/p, Where h is the Planck constant and p is the momentum of the particle
Wave Function
the square of the wave function amplitude is proportional to the probability density - the probability of finding a particle within a given volume.
Heisenberg’s Uncertainty Principle
There is a fundamental limit to the degree of precision with which certain pairs of physical properties (eg. Position and momentum; Energy and time) can be measured.
Count Rate
the number of ‘counts’ per second, as measured by a Geiger counter.
