definitons Flashcards
Absolute luminosity?
The brightness that a start would have at a standard distance of 10 parsec.
Absolute zero?
The zero of thermodynamic temperature, 0K =-273.15 degrees C
Absorbed Dose?
The number of joules of energy absorbed from an ionising radiation per kilogram of tissue, measured in Grays (Gy) where 1 Gy = 1J/Kg
Acceleration?
Rate of change of velocity, a=dv/dt
Activation energy?
E, a certain amount of energy that is needed to make a specific process occur.
Activity?
The number of nuclei in a radioactive source decaying per second. Measured in Becquerels (Bq)
Alloy?
A material composed of 2 or more metals or metals and other materials.
Alternating current?
A current alternating sinusoidally produced by an alternating pd in a circuit.
Amorphous?
A material with no long range order. E.g. Glass forms strong bonds between atoms and make up a rigid structure without any regularity.
Amount of a substance?
The number of molecules, atoms or ions in a certain structure.
n= N/N[A]
Ampere (A)?
The S.I. unit of electrical current. 1A = 1c/s
Amplitude?
The greatest displacement of an oscillator from its equilibrium position.
Angular frequency?
The angle (in radians) moved per second.
Where w = theta/time
Antinode?
A position of maximum amplitude of oscillation in a standing wave.
Antiparticle?
An anti- and particle counterpart have equal but opposite electrical charge (or both uncharged) and equal rest energy. Opposite spins.
