Nuclear Physics Flashcards
(12 cards)
What does a mass defect mean?
It is defined as the difference between the total mass of the separate nucleons in a nucleus and the combines mass of the nucleus
Define Binding energy
It is defined as the energy of required to separate the nucleons in a nucleus to infinity. It is also the energy equivalent of the mass defect of a nucleus.
Define binding energy per nucleon
It is defined as the average energy per nucleon needed to separate a nucleus into its constituent nucleons to infinity.
Define radioactive decay
It is spontaneous and random process in which an unstable nucleus emits alpha particles, beta particles of gamma radiation to become more stable.
Define exponential decrease
It refers to a situation where a quantity reduces at a rate proportional to its current value.
Define half life
Half life of a radioactive nuclei is the time taken for the number of undecayed nuclei to be reduced to half of its original number.
What does it mean by activity
The activity of a radioactive source is defined as the number of nuclear disintegrations per unit time in the source.
What does spontaneous decay mean?
It is one which is not triggered or affected by external factors such as temperature and pressure.
What does it mean by a random decay?
It is one in which it cannot be predicted which nucleus will decay next.
What is the penetrating power of alpha particles?
Weak, can be stopped by a piece of paper. Range in air is only a few cm.
What is the penetrating power of beta particles?
Moderate, can be stopped by a few mm of aluminium. Range in air is only about a metre.
What is the penetrating powet of gamma radiation?
The strongest, can only be stopped by at least 10cm of lead shielding. Penetrated almost unlimited thickness of air and several metres of concrete.