Physics flashcards

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  • Created by: Sara
  • Created on: 27-03-13 14:30
Absolute Scale
Temperature scale in kelvins defined in the terms of absolute zero, 0K, and the triple point of water, 273K
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Absolute Zero
The lowest possible temperature, the temperature at which an object has minimum internal energy
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Absolute Temperature (K)
In kelvin = temperature in Celsius + 273
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Activity (Bq)
The number of nuclei of the isotope that disintegrate per second
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Alpha Decay
Change in an unstable nucleus when it emits an alpha particle, consisting of 2 protons and 2 neutrons. It's absorbed by paper and has a range of a few centimeters, and is the most ionising
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Atomic Mass Unit
The unified atomic mass constant, 1/12th of the mass of an atom of carbon-12, equal to 1.661x10^-27 kg
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Atomic Number
The number of protons in the nucleus of an atom
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Avogadro Constant
The number of atoms in 12g of carbon-12, used to define the mole. 6.02x10^23
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Background Radiation
Radiation due to naturally occurring radioactive substances in the environment and cosmic radiation
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Beta-minus Radiation
B- emitted (and an antineutrino) by an unstable neutron-rich nucleus. It is easily absorbed by aluminium, range of a few centimeters and less ionising than alpha, but more than gamma
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Beta-plus Radiation
B+ emitted (and a neutrino) by an unstable proton-rich nucleus. Travel no further than 2mm before annihilated
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Binding Energy of a Nucleus
The work that must be done to separate a nucleus into its constituent neutrons and protons. MeV= mass defect (u) x 931.3
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Binding Energy per Nucleon
The average work done per nucleon to separate a nucleon into its constituent parts. E per nucleon = E/mass number
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Boiling Point
The temperature at which a pure liquid at atmospheric pressure boils
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Boyle's Law
For a fixed mass of gas at constant temperature, its pressure x volume is constant
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Boltzmann Constant
The molar gas constant/Avogadro number
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Brownian Motion
The random and unpredictable motion of a particle such as a smoke particle caused by molecules of the surrounding substance colliding at random with the particle
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Chain Reaction
A series of reactions in which each reaction causes a further reaction. In a nuclear reactor, each fission event is due to a neutron colliding with a U nucleus, which splits and releases 2/3 further neutrons
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Steady Chain Reaction
One fission neutron on average from each fission event produces a further fission event
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Charles' Law
For an ideal gas at constant pressure, its volume is directly proportional to its absolute temperature
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Control Rods
Rods made of a neutron-absorbing substance (Cadmium) that are moved in or out of the core of a nuclear reactor to control the rate of fission events
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Coolant
A fluid taht is used to prevent a machine from over heating. In a nuclear reactor, the coolant is pumped through the core to transfer thermal energy to a heat exchanger
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Count Rate
The number of counts per unit time detected by a Geiger Muller tube. Count rates are corrected by measuring and subtracting the background radiation
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Critical Mass
The minimum mass of the fissile isotope in a nuclear reactor necessary to produce a chain reaction
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Decay Constant
The probability of an individual nucleus decaying per second
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Decay Curve
An exponential decrease curve showing how the mass or activity of a radioactive isotope decreases with time
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Dose Equivalent (Sv)
The energy that would need to be absorbed per unit mass of matter
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Electron
Rest mass: 9.11x10^-31 Electric charge: -1.6x10^-19
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Electron Capture
A proton-rich nucleus captures an inner-shell electron to cause it to change into a neutron (neutrino emitted, and X-ray photon emitted when inner shell full)
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Excited State
An atom which is not in its ground state
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Fission
The splitting of a U or Pu nucleus into two approximately equal fragments
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Induced Fission
Fission caused by an incoming neutron colliding with a U or Pu nucleus
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Fission Neutrons
Neutrons released when a nucleus undergoes fission and which may collide with nuclei to cause further fission
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Nuclear Fusion
The fusing together of light nuclei to a form a heavier nucleus
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Gamma Radiation
Electromagnetic radiation emitted by an unstable nucleus when it becomes more stable. Gamma is the least ionising, but most penetrative
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Ground State
The lowest energy state of an atom
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Half-life
The time taken for the mass of a radioactive isotope to decrease to half the initial mass or for its activity to halve - time taken for number of nuclei to halve
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Heat (Q)
Energy transfer due to a difference of temperature
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Heat Capacity
The energy needed to change the temperature of an object by 1K
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Heat Exchanger
Hot coolant is pumped through this to cause water to turn to steam and drive turbines
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Ideal Gas
A gas under conditions such that it obeys Boyle's law
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Ideal Gas Equation
pV = nRT (n is the number of moles, R is the molar constant)
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Intensity of Radiation (Wm-2)
The radiation energy per second per unit area at normal incidence to the surface
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Internal Energy
The sum of the random distribution of the kinetic and potential energies of its molecules
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Ionising Radiation
Radiation that produces ions in the substances it passes through. Destroys cell membranes and damages DNA
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Isotopes
Atoms which have the same number of protons in each nucleus but different numbers of neutrons
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Kinetic Energy of molecules (ideal gas)
Mean kinetic energy = 3/2kT. Total kinetic energy = 3/2nkT
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Kinetic Theory of a gas
Molecules in continual random motion so pressure is pV = 1/3Nmc2
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Latent Heat of Fusion
The energy needed to change the state of a solid to a liquid without change of temperature
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Latent Heat of Vapourisation
The energy needed to change the state of a liquid to a vapour without change of temperature
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Mass Defect
The difference between the mass of separated nucleons and the nucleus
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Melting Point
The temperature at which a pure substance melts
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Metastable State
An excited state of the nuclei of an isotope that lasts long enough after alpha or beta emission for the isotope to be separated from the parent isotope
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Moderator
Substance in a thermal nuclear reactor that slows down the fission neutrons so they can go on to produce further fission
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Neutron
Uncharged particle with a rest mass of 1.675x10^-27 kg
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Nucleus
The relatively small part of an atom where all the atom's positive charge and most of its mass is concentrated (1/10th size of the atom)
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Pair Production
When a gamma photon changes into a particle and antiparticle
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Photon
Wave packet of electromagnetic radiation. E=hf
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Pressure Law (for an ideal gas)
Its pressure is directly proportional to its absolute temperature
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Proton
A particle with equal and opposite charge to an electron. Rest mass of 1.673 x 10^-27 kg
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Rutherford's alpha-particle experiment
Demonstrated every atom contains a positively charges nucleus which is much smaller than the atom
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Strong Nuclear Force
Force that holds the nucleons together. Range of 2-3fm, and below 0.5fm, it is repulsive
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Sublimation
The change of state when a solid changes to vapour directly
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Thermal Equilibrium
When no overall heat transfer occurs between two objects at the same temperature
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Thermal Nuclear Reactor
Nuclear reactor which has a moderator in the core
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Other cards in this set

Card 2

Front

The lowest possible temperature, the temperature at which an object has minimum internal energy

Back

Absolute Zero

Card 3

Front

In kelvin = temperature in Celsius + 273

Back

Preview of the back of card 3

Card 4

Front

The number of nuclei of the isotope that disintegrate per second

Back

Preview of the back of card 4

Card 5

Front

Change in an unstable nucleus when it emits an alpha particle, consisting of 2 protons and 2 neutrons. It's absorbed by paper and has a range of a few centimeters, and is the most ionising

Back

Preview of the back of card 5
View more cards

Comments

Samoknight

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Some of the flash cards explain things in an overly complicated way. Still a good resources, but needs a bit of fine tuning.

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