Definitions Flashcards
Isotope
Isotopes are atoms with the same number of protons but difference numbers of neutrons
Pair Production
When a photon decays and creates a particle and its corresponding anti-particle near to a nucleus
Leptons
Leptons interact through the weak nuclear force and the electromagnetic force if they are charged these are fundamental
Hadrons
Hadrons interact through the strong nuclear force and the electromagnetic force if they are charged. Apart from the proton, Hadrons decay through the weak interaction
Baryons
Are particles that contain 3 quarks. Protons are hadrons and all other hadrons decay into protons
Mesons
Are Hadrons that contain a quark and an anti-quark and do not include protons in their decay products.
Strangeness
Always conserved in a Strong interaction, particles that contain Strange or anti-strange quarks
Energy, Momentum, Charge, Baryon number and Lepton number
Are always conserved
Work Function
The minimum energy required by an electron to escape from a metal surface
Threshold Frequency
The minimum frequency of radiation of a photon required to release an electron from a metal surface
Ionisation
The energy required to remove an electron from an atom from the ground state.
Electron-volt
The work done on an electron accelerating it through a potential difference of one volt.
Fluorescence
Materials that absorb UV radiation and when the electrons de-excite they release photons of visible frequencies
Potential Difference
The work done per unit charge
Electro-motive force
The electrical energy produced per unit charge passing through the source
Ohm’s Law
The potential difference across a metallic conductor is proportional to the current through it provided the physical conditions do not change
Resistivity
The resistance of a material of length l and cross sectional area A
Critical Temperature
A material that has zero resistivity below the critical temperature is a superconductor
Kirchoff’s first law
The sum of the currents going into a junction equals the sum of the currents coming out of the junction
Kirchoff’s second law
The sum of the emfs equals the sum of the pds in any closed loop
Power
Rate at which energy is transferred
Internal resistance
The internal resistance of a source is the loss of potential difference per unit current in the source when the current passes through the source