radiation Flashcards
describe an alpha particle
2 protons, 2 neutrons, helium nuclei. charge = +2
describe a beta particle
it has fast moving electrons charge = -1
describe gamma rays
they are high energy electromagnetic waves, low ionising
what is ionisation
the addition of removal of an electron from a neutral atom leaving it charged
give example of natural radiation
cosmic rays
radon gas
food and drinks
give examples of man made radiation
x-rays
nuclear
indirect medical testing
what is activity
the number of radioactive decays each second
formula for activity
A= N/T
(unit becquerels)
(number of decays / time)
what is a half life
amount of time it takes for activity to fall to half of its original value.
what can we use to detect radiation?
a geiger counter
photographic film darkens when exposed
what is absorbed dose
the amount of energy absorbed by each kg of material.
how do you find absorbed dose
A= E/M
energy absorbed/ mass
what does biological harm depend on
absorbed dose
type of radiation
type of body tissue
distance from the source
what is biological harm
equivalent dose
formula for equivalent dose?
H=DxWr
absorbed dose x radiation weighting factor
