Chapter 3 Exam Flashcards
an electric and magnetic disturbance traveling through space at the speed of light
Electromagnetic radiation
properties of electromagnetic radiation
Can exist apart from matter
Is a form of energy that originates from the atom
Can travel through a vacuum
a way of ordering or grouping the different electromagnetic radiations
Electromagnetic spectrum
Have the same velocity (the speed of light 3 x 10^8 m/s)
Vary only in their energy, wavelength, and frequency
properties of electromagnetic spectrum
all EM radiation diverges from the source spreading the intensity of the radiation over a larger area
Divergent rays
______ = flow per second (# of protons)
energy
As x-rays travel their intensity _______
decreases
inverse square law
I1 (d2)^2
— = ———-
I2 (d1)^2
what do the I and d represent in the inverse square law?
I = intensity (luminosity)
d = distance
EM radiation exhibits properties of a wave or particle depending on its energy
wave-particle duality (E=mc^2)
distance between waves
wavelength
how often the waves occur
frequency
how tall the waves are
amplitude
the relationship between wavelength and frequency is ______
inverse
frequency is expressed in:
(one cycle per second)
hertz (Hz)
wavelength or frequency formula
velocity = frequency x wavelength (v=fλ)
at the low end of the spectrum
used in MRI
non-ionizing radiation
radiowaves
ionizing radiation creates a:
permanent change
non-ionizing radiation creates a:
temporary change
positively charged beta particle is called a:
positron
x-ray cannot get through, it is absorbed
ex: bone
radiopaque
x-ray can get through, it is not absorbed
ex: soft tissue
radiolucent
_____ and _____ are used for imaging in radiology and nuclear medicine
x-ray, gamma rays
has the ability to ionize matter
x-rays and gamma rays
all electromagnetic radiation is very similar in that it has no mass, carries energy in waves as electric and magnetic disturbances in space, and travels at the speed of light
james maxwell’s theory
All members of the electromagnetic spectrum have the same _______ (the speed of light or
3 x 10^8 m/s) and vary only in their ______, _______, and _______.
velocity, energy, wavelength, frequency
Members of electromagnetic spectrum from lowest to highest energy
Radiowaves
Microwaves
Infrared light
Visible light
Ultraviolet light
X-rays
Gamma rays
Wavelengths on the electromagnetic spectrum range from ____ to ____ meters (m)
10^6 to 10^-16
Frequencies on the electromagnetic spectrum range from ____ to ____ hertz (Hz)
10^2 to 10^24
Energy on the electromagnetic spectrum ranges from ____ to ____ electron volts (eV)
10^-12 to 10^10
Energy of electromagnetic radiation can be calculated by:
E = hf
E = hf
E is energy
h is Planck’s constant (4.135 x 10^15 eV sec; 6.626 x 10^-34 J sec)
f is the frequency of the photon
as frequency increases, so does ______
energy
the idea that there are two equally correct ways to describe electromagnetic radiation
Wave-particle duality
refers to the maximum height of a wave
Amplitude
velocity = frequency x wavelength (v=fλ)
v gets replaced with:
c (constant symbol for speed of light: 3 x 10^8 m/s)
when a photon possesses sufficient energy it can remove electrons from the orbit of atoms during interactions
Ionization
removal of an electron from the atom
The atom and electron that was removed from it are called an ion pair
properties of ionization
originate in the nuclei of atoms and represent the excess energy the atom is giving off to reach a stable state
gamma rays
originate through interactions between electrons and atoms
x-rays
a low-energy, electromagnetic radiation just above microwaves
infrared light
represents the colors visible to the human eye
visible light
has energies approaching those of x-rays and gamma rays
Can be harmful and routine exposure has been demonstrated to cause skin cancer
ultraviolet light
physical particles originating from radioactive atoms and have the energy to ionize matter
Particulate radiation (alpha and beta particles)
the process by which an atom with excess energy in its nucleus emits particles and energy to regain stability
Radioactivity
the process of a radioactive element giving off excess energy and particles to regain stability
Radioactive decay
the length of time it takes for half the remaining atoms in a quantity of a particular radioactive element to decay
Half-life
The measure of radioactive decay is the
Becquerel (curie)
two protons bound to two neutrons
alpha particle
an electron that is emitted from an unstable nucleus, it does not originate in an electron shell
Have much larger range and may ionize many atoms along their path
beta particle
_______ charged beta particles differ from electrons only in that it originated in the nucleus and not an orbital shell
negatively
As the frequency of the electromagnetic radiation decreases, wavelength will:
increase
Which of the following members of the electromagnetic spectrum has the ability to ionize matter?
X-rays
Which of the following is not within the wavelength range of electromagnetic radiation?
10^-24
Which member of the electromagnetic spectrum has the longest wavelength?
radiowaves
A diagnostic x-ray photon has a frequency of 2.42 x 10^19 Hz. What is its wavelength?
1.24 x 10^-11 m
A photon has a wavelength of 3 x 10^-12 m. What is its frequency?
1 x 10^20 Hz
Which of the following do not originate from an unstable nucleus?
X-rays
How much activity will remain in a dose of 20 mCI 99mTC after 24 hours? (the physical half-life of 99mTc is 6 hours)
1.25 mCi
The intensity of a source at 15 inches is 10 R. What will the intensity be at 45 inches?
1.11 R
The intensity of a source is 25 R at 40 inches. What will the intensity be at 20 inches?
100 R
