RADIATION SAFETY STUDY GUIDE
EXAM QUESTIONS WITH CORRECT
ANSWERS
Parent - answer-the original isotope prior to radioactive decay
Daughter - answer-the isotope after the transformation
Decay or disintegration - answer-a given transformation, that is, one parent/daughter
transition
The rate of radioactive decay, also called the disintegration rate or decay rate, is used
to indicate what? - answer-the "radioactivity" of a sample and is termed the "activity"
What is a nuclide comprised of? - answer-any specific nuclear combination of neutrons
and protons
Radionuclide - answer-an unstable nuclide (any specific nuclear combo of neurons and
protons)
The half-life corresponds to the time necessary for one-half of the radioactive atoms of a
sample to decay. The fraction of atoms (or activity) remaining as a function of the
number of elapsed half-lives is what? - answer-fraction remaining = (1/2)nth
1/2 (50%) of the activity remains after 1 half-life,
1/4 (25%) after 2 half-lives,
1/8 (12.5%) after 3 half-lives,
And so on.
With a starting activity of 40 mci, what is the activity left after 4 half lives? - answer-
2.5mci.
1/2 of 40 is 20,
1/2 of 20 is 10,
Half of 10 is 5,
Half of 5 is 2.5.
What is the half life of phosphorus-32? - answer-14.3 days
What is the half life of carbon-14? - answer-5700 years
What is the half life of hydrogen-3? - answer-12.3 years
, Electron volt - answer-a unit of energy, denotes particle and photon energies,
represents the energy change experienced by an electron while undergoing a potential
energy change of one volt
What happens in alpha decay? - answer-a charged particle (alpha particle) consisting of
two protons and two neutrons, is ejected from the nucleus with high kinetic energy -
typically, about 4 mev
How is the alpha particle stopped? - answer-initial energy is great, the particle is
stopped by a few centimeters of air or a few microns of tissue
Beta decay - answer-transition that results in the emission of an electron from the
nucleus, may be negatively (electron) or positively charged (positron)
In the case of simple beta decay, the only detectable radiation emitted during the decay
process is what? - answer-the beta particle
Gamma ray - answer-a photon of electromagnetic radiation
It is more common for the daughter to be in an excited isomeric state of the nuclide with
what? - answer-a subsequent emission from the nucleus (usually promptly) of a photon
of electromagnetic radiation, called a "gamma ray"
What are x- and y- rays? - answer-electromagnetic radiation
X-rays are emitted by what? - answer-electrons
Y-rays are emitted by what? - answer-the nucleus of an atom involved in radioactive
decay
Photoelectric absorption - answer-photon is absorbed by a bound electron that is in an
atom of the material with which the photon interacts and the photon ceases to exist. The
electron is ejected from its previously bound state and carries away most of the
absorbed energy as kinetic energy
The probability of photoelectric absorption is dependent upon the energy of the radiation
and upon the atomic number of the absorbing material. What does this mean? - answer-
photoelectric absorption is the dominant absorption process at low radiation energies. It
occurs, for a given energy, much more in materials of high atomic number than in
materials with low atomic number. Thus, lead with the high atomic number of 82, is an
excellent material for absorbing radiation by the photoelectric process
Compton scattering - answer-in this interaction the incident photon undergoes a billiard-
ball type collision with an electron of the interacting material. The photon is deflected, or
"scattered", by the collision and continues on with reduced energy. Occur to about the
EXAM QUESTIONS WITH CORRECT
ANSWERS
Parent - answer-the original isotope prior to radioactive decay
Daughter - answer-the isotope after the transformation
Decay or disintegration - answer-a given transformation, that is, one parent/daughter
transition
The rate of radioactive decay, also called the disintegration rate or decay rate, is used
to indicate what? - answer-the "radioactivity" of a sample and is termed the "activity"
What is a nuclide comprised of? - answer-any specific nuclear combination of neutrons
and protons
Radionuclide - answer-an unstable nuclide (any specific nuclear combo of neurons and
protons)
The half-life corresponds to the time necessary for one-half of the radioactive atoms of a
sample to decay. The fraction of atoms (or activity) remaining as a function of the
number of elapsed half-lives is what? - answer-fraction remaining = (1/2)nth
1/2 (50%) of the activity remains after 1 half-life,
1/4 (25%) after 2 half-lives,
1/8 (12.5%) after 3 half-lives,
And so on.
With a starting activity of 40 mci, what is the activity left after 4 half lives? - answer-
2.5mci.
1/2 of 40 is 20,
1/2 of 20 is 10,
Half of 10 is 5,
Half of 5 is 2.5.
What is the half life of phosphorus-32? - answer-14.3 days
What is the half life of carbon-14? - answer-5700 years
What is the half life of hydrogen-3? - answer-12.3 years
, Electron volt - answer-a unit of energy, denotes particle and photon energies,
represents the energy change experienced by an electron while undergoing a potential
energy change of one volt
What happens in alpha decay? - answer-a charged particle (alpha particle) consisting of
two protons and two neutrons, is ejected from the nucleus with high kinetic energy -
typically, about 4 mev
How is the alpha particle stopped? - answer-initial energy is great, the particle is
stopped by a few centimeters of air or a few microns of tissue
Beta decay - answer-transition that results in the emission of an electron from the
nucleus, may be negatively (electron) or positively charged (positron)
In the case of simple beta decay, the only detectable radiation emitted during the decay
process is what? - answer-the beta particle
Gamma ray - answer-a photon of electromagnetic radiation
It is more common for the daughter to be in an excited isomeric state of the nuclide with
what? - answer-a subsequent emission from the nucleus (usually promptly) of a photon
of electromagnetic radiation, called a "gamma ray"
What are x- and y- rays? - answer-electromagnetic radiation
X-rays are emitted by what? - answer-electrons
Y-rays are emitted by what? - answer-the nucleus of an atom involved in radioactive
decay
Photoelectric absorption - answer-photon is absorbed by a bound electron that is in an
atom of the material with which the photon interacts and the photon ceases to exist. The
electron is ejected from its previously bound state and carries away most of the
absorbed energy as kinetic energy
The probability of photoelectric absorption is dependent upon the energy of the radiation
and upon the atomic number of the absorbing material. What does this mean? - answer-
photoelectric absorption is the dominant absorption process at low radiation energies. It
occurs, for a given energy, much more in materials of high atomic number than in
materials with low atomic number. Thus, lead with the high atomic number of 82, is an
excellent material for absorbing radiation by the photoelectric process
Compton scattering - answer-in this interaction the incident photon undergoes a billiard-
ball type collision with an electron of the interacting material. The photon is deflected, or
"scattered", by the collision and continues on with reduced energy. Occur to about the
