Definitions Flashcards
What is absolute temperature?
Any temperature scale that starts at absolute zero
What is absolute zero?
The theoretical temperature at which molecules will no longer be moving, all kinetic energy has been removed
What is activity? (Radiation)
The number of radioactive decays in unit time
What is an alpha particle?
Particles compose of 2 protons and 2 neutrons, the same as a helium nucleus
What is alpha decay?
The radioactive process in which a particle of combination 2 protons and 2 neutrons is ejected from a nucleus
What is angular displacement?
The vector measurement of the angle through which something has moved
What is annihilation?
The phenomenon in which a particle and its anti-matter equivalent are both destroyed simultaneously in a conversion into energy which is carried away by force carrier particles such as photons
What is an anti-particle?
For each particle there exists and anti-particle, which has the same mass but all their other properties are opposite to those of the normal matter particle.
What is an astronomical unit?
The radius of the Earth’s orbit around the sun. 1 AU=1.5x10^11
What is atomic number?
An alternative name for proton number, the number of protons in the nucleus of an atom
What is background radiation?
Low levels of radiation from environmental sources, always present around us
What is a baryon?
A particle made of a combination of 3 quarks
What is baryon number?
The quantum number for baryons, whereby each proton or neutron (or other baryon) has a value of B=1
What is a beta particle?
An electron emitted at high speed from the nucleus when a neutron decays into a proton
What is beta-minus decay?
The radioactive process in which a nuclear neutron changes into a proton, and an electron is ejected from the nucleus
What is the Big Bang?
The theory that the universe expanded outwards, from a single point to the currently observed situation
What is the Big Crunch?
A possible future for the universe, in which it contracts inwards to a single point
What is binding energy?
The energy used to hold the nucleus together, converted from the mass deficit, following E=mc^2
What is a black body radiator?
A theoretical object that completely absorbs all radiation that lands on it
What is a black dwarf?
The final stage of the life cycle of a small mass star, when nuclear fusion has ceased and it has cooled so that it no longer emits visible light
What is a black hole?
One of the possible conclusions to the life of a large mass star; a region of space-time in which the gravity is so strong that it prevents anything from escaping including EM radiation
What is a blue supergiant?
A very large, very hot star, perhaps 25,000K
What is Boyle’s law?
Boyle’s law states that for a constant mass of gas at a constant temperature, the pressure exerted by the gas is inversely proportional to the volume it occupies
What is a bubble chamber?
A particle detection system in which the particles trigger bubbles to be created in a superheated liquid, typically hydrogen