Definitions Flashcards
Alpha
A helium nucleus (4-2-He)
That moves only a few cm in air and cannot penetrate skin
Very ionising
Nucleon
particles found in the nucleus- protons and neutrons
Beta +
Fast moving positron
Decreases proton number by 1 in Beta+ emission
Beta -
Fast moving electron
Increases proton number by 1 in Beta- emission
Gamma
High frequency/energy Electro-Magnetic wave (travels at the speed of light, highly penetrating, not very ionising)
(Cannot be completely stopped, only slowed or reduced)
Fission
The splitting on large unstable nuclei to form smaller more stable nuclei
Fusion
The joining of 2 small nuclei to form bigger, more stable nuclei
Binding energy
The energy required to break a nucleus into its constituent parts
Mass Defect
The difference in mass between the nucleus and its constituent parts
Random (in terms of decay)
You cannot predict which nucleus will decay NEXT
Spontaneous (in terms of decay)
Cannot be influenced by external factors (e.g. Temperature)
So we cannot control the speed or amount of decay
Half life
The amount of time it takes for half of the undecayed nuclei to decay
Isotope
An atom with the same number of protons, different number of neutrons
SHM (Simple Harmonic Motion)
An oscillation in which the acceleration of an object is directly proportional to its displacement from the midpoint, and is directed towards the midpoint
Resonance
When the driving frequency is equal to the natural frequency
(the system gains energy from the driving force and vibrates with a rapidly increasing amplitude)
Damping
Reduces the amplitude if the oscillation over time. The heavier the damping, the quicker the amplitude is reduced to zero.
Gravitational field lines
Arrows showing the direction of the force that masses would feel in a gravitational field
Gravitational field strength
The force per unit mass (g)
g=F/m
Satellite
A smaller mass which orbits a much larger mass
Magnetic Field
A region where a force is exerted on magnetic material
Capacitance
The amount of charge stored per volt
Hadrons
Particles that feel the strong interaction (protons and neutrons)
Baryon
Particle with 3 quarks (e.g. protons and neutrons)
Meson
Particle with 1 quark and 1 antiquark
(E.g. Pions and Kaons)
-unstable
Baryon number
The number of baryons in a reaction
Leptons
Don’t feel the strong interaction (e.g. Electrons and neutrinos)
Cyclotron
Circular particle accelerator
Boyle’s Law
At a constant temperature the pressure and volume of a gas are inversely proportional
Charles’ Law
At constant pressure, the volume or a gas is directly proportional to the absolute temperature
The pressure law
At constant volume, the pressure of a gas is directly proportional to ta absolute temperature
Electric potential
Potential energy per unit charge
Faraday’s Law
The induced EMF is directly proportional to the rate of change of flux linkage
Lenz’s law
The induced EMF is always in such a direction as to oppose the change that caused it
Specific heat capacity
The energy transfer needed to change the temperature of 1kg of a substance by 1 Kelvin
Ideal Gas
A gas that obeys Boyle’s law at all temperatures
Background radiation
The radiation that is present at all times in our environment
Luminosity
The total power emitted by a star (the unit is the Watt)
Radiant Flux
The power per unit area received by an observer (the unit is the Wm^-2)
Light year
9.5 x 10^15 m
Hubble’s Law
The recessional speed of galaxies is directly proportional to the distance from the point of observation
