Electromagnetic Radiation Ch. 4- Test 2 Flashcards
A long wavelength = more or less frequency than a short wavelength?
LESS frequently than a short wavelength
All electromagnetic energy is under, what law?
Inverse square law
What is a disturbance in any medium (such as water) that transports energy from one place to another without causing any permanent change in the medium?
Waves
Waves transfer energy
A ____ wave that oscillates perpendicularly to the direction of the wave’s travel.
(Perpendicular Displacement)
Give an example
Transverse Wave
- Ex. Water Waves in the Ocean, EM Waves (Light Rays, Radio Rays, X Rays, Gamma Rays, etc.)
-
___ or ____ waves are displacement of the medium parallel to the direction of wave travel
(Parallel Displacement)
Give an example
Longitudinal or Compressional Waves
-Ex. Sound Waves
What are the four characteristics of all waves?
Speed
Amplitude
Wavelength
Frequency
Define amplitude:
Give an example
The maximum displacement of the medium
Essentially representing the “height” of the wave from its resting point to its peak or trough, and indicating the strength or intensity of the wave; a larger amplitude means more energy is carried by the wave
- Ex. Height of water waves
A larger amplitude of a wave means what?
More energy is carried by the wave
What is the top part of a wave known as?
The crest
What is the bottom part of a wave known as?
Trough
How do you measure the amplitude of a Transverse Wave?
One-half the distance from the trough to the crest
How do you measure compressional waves?
distance from the middle of an expansion to the middle of a compression (one-half the wavelength)
Can be measured from any point on a wave, as long as it is measured to the same point on the next wave
Look at photo for a visual
How do you measure wavelength?
How do you measure wavelength for Transverse Waves and Compressional Waves?
Measured between two like points along the waveform
For transverse waves, crest to crest
For compressional waves, middle of an expansion to the middle of the next expansion
____ is one completion of the waveform (before it repeats itself)
Wave Cycle
Each wave cycle consists of two ______, one ______ and one _______
Pulses
Positive
Negetive
____ is the number of cycles (waves) that pass by a given point each second
Frequency
What is the unit for frequency?
Hertz, abbreviated Hz
Changing the ______ or the ________ will alter the frequency of a series of waves.
Speed
Wavelength
For a given wavelength, speeding up the waves from 5 to 10 mph will ___ the frequency.
Increase
For a given speed, ___ the wavelength of the waves will increase the frequency.
The amplitude height of the wave is measured in:
Meters or cm
The reciprocal of the time between crests passing a point or the period of the vibration is:
Frequency
Frequency is also written as:
v (Greek letter nu, not velocity)
The Greek letter lambda is equivalent to what English letter?
L, which you may associate with “length” or “wavelength”
For a given fixed wavelength, what is the relationship between speed and frequency?
Directly Proportional, meaning as one increases so does the other
This relationship is expressed by the formula; speed = wavelength x frequency
For a given fixed frequency, what is the relationship between speed (velocity) and wavelength?
Directly Proportional
Traveling at twice the speed, the waves would have to be twice as long to strike you at the same rate per second
For a given fixed speed, what is the relationship between frequency and wavelength?
Inversely Proportional
If the frequency is doubled, the wavelength must have been cut in half to maintain the same speed
Review Slides
25
28
& Solve
You have __ wave every 2 seconds.
one
What does Electromagnetic Waves include?
Radio Waves / TV Waves
Radar
Microwaves
Infrared Light
Visible Light
Ultraviolet Light
Gamma Rays
Cosmic Rays
How are electromagnetic waves different than water waves?
They do not require a medium to travel through, meaning they always travel the same speed in a vacuum such as outer space, while water waves need a physical medium like water to move; also electromagnetic waves are composed of oscillating electric and magnetic fields, unlike water waves which involve the movement of water molecules themselves.
What is the speed of light is:
3 x 10^8 meters/sec
When using the Electromagnetic Wave Formula, what does v represent?
Speed of light
3 x 10^8 m/s
Practice Problem on Slide 36
Electromagnetic Radiation is ____ related to the square of the distance from the source.
Inversely
What is the reason for the rapid decrease in intensity, with increasing distance?
The total light/x-ray intensity emitted is spread out over an increasingly larger area
What is the inverse square formula?
Slide 40
Write it out
What does Planck’s simple formula show?
for quanta (the smallest possible amount of physical property, x-rays and all other electromagnetic radiation) their energy is directly proportional to their frequency
What is the Planck Formula and what does it state?
E = hf
States that the energy (E) of a photon is directly proportional to its frequency
What is the Planck constant expressed in?
Joulexseconds
The Energy and Frequency of a photon are ___ proportional
Directly meaning as the frequency of a photon increases, its energy also increases proportionally
Wavelength and Energy are ____ proportional
Inversely this means that as wavelength increases, energy decreases, and vice versa
The higher the energy, the __ the wavelength, and the ___ the frequency.
Shorter
Higher
X-ray photons, unlike the rest of the electromagnetic spectrum, are identified by their energy measured in ___
Electron Volts (eV)
X-ray energies range from __ keV to __ MeV
10
50
Energy relates to ___
Penetrating Power
1 electron volt (eV) =
1 electron volt (eV) is the amount of energy gained by an electron when it is accelerated through an electric potential difference of 1 volt.
1.6 x 10^19 joules
If the energy of an x-ray doubles, its frequency as an electromagnetic wave must ____
Also double
For x-rays, their energy and wavelength are always ___ proportional to each other.
For example, the higher the voltage (kVp), the shorter the ___
- inversely
- wavelength
Review Plancks Practice
Slide 56
How do you convert keV to eV?
you multiply by 1,000, because 1keV= 1,000 eV
What does the Law of Conservation of Matter/ Energy state?
That matter can neither be created nor destroyed
Nuclear fission:
Matter into energy
Pair Production:
Energy into mass
Solve the problem on slide 63
(Emily whiteboard)
1eV = ___ joules
1.602 x 10^19 joules
To find the kilovoltage or the wavelength of an x-ray from each other, what is the formula?
kVp= 12.4/λ
What is Planck’s constant “h”? for joules per second?
6.62 x 10⁻³⁴
Any moving electrical charge generates a magnetic field around it along with its electrical field. Aligned with its poles, the magnetic field is always ____ to the electrical field.
Perpendicular
Each proton and electron has ____, a type of movement in which generates a magnetic field around the particle even when it is “sitting still”.
Do electrons have to be traveling down a wire in the form of electricity in order to possess a magnetic field?
- Spin
- No!
We all have a magnetic field around yes, true or false?
True
Oscillation of an electron up and down creates a wave disturbance in the __ and ___ fields surrounding it, which travel outward.
Magnetic and Electric Fields
Radio waves, x-rays, and all other kinds of electromagnetic waves are _______ waves, of the ______ type, consisting of a magnetic wave that runs perpendicular to a wave in the electrical field
- Double-waves
- Transverse
A ______ describes anything that can be measured in an orderly, continuous progression of a minute degrees, or a broad range of values
Spectrum
The entire band of electromagnetic energies is known as the _____
Electromagnetic Spectrum
At different energy levels, how are the radiations distinguished in the electromagnetic spectrum?
by the different ways they react with molecules and particles
A ____ is considered the smallest discrete quantity (or “quantum”) of electromagnetic energy
Photon
______ is typically the natural frequency in which all structures, molecules, atoms, and even subatomic particles are “tuned”
Resonance
If a radiation wave encounters an object & its frequency matches the object, what happens?
It is absorbed
If a radiation wave encounters an object & its frequency differs from the object, what happens?
it will penetrate through it
What does “RADAR” stand for?
Radio Detection and Ranging
How do microwaves heat your food?
Tuse a resonator that is stimulated by the emission of radiation to synchronize the “micro-waves”. bring these waves in phase with each other boosts their amplitude enough to warm the food
Infrared has energies (below/above) visible light?
Just below
Which ones use “x-rays”?
DR & CR
CR readers
CT
nuclear medicine
radiation therapy
MRI
sonography
laser surgery
laser readers
DR & CR
CT
Ultraviolet has energies (below/above) visible light?
Above
In order from longest wavelength to shortest, the electromagnetic spectrum goes:
Radiowaves
Microwaves
Light Waves
X Rays
Gamma Rays
Which ones use “gamma rays”?
DR & CR
CR readers
CT
nuclear medicine
radiation therapy
MRI
sonography
laser surgery
laser readers
nuclear medicine
radiation therapy
How is an MRI scan completed, at an electromagnetic level?
Protons inside a patient align with the magnetic field… once a certain strength is reached, the protons begin to “wobble” at a known rate. they are then “knocked over” with a radio pulse and spiral back up to realign with the magnetic field. they then emit their own radio waves
t/f. Similar to light, sound waves follow basic laws of reflection and refraction
True
Why must gel be used during a sonography exam?
To avoid any gas/air pockets between the transducer and the skin, which can completely scatter and diffuse the sound waves coming out of the transducer
What does “laser” stand for?
light amplifications by stimulated emission of radiation
What are the 3 major components of a laser?
- a medium (provides stimulation for the atom)
- a power source/pumping source (stimulation for the atoms)
- a resonant cavity (amplifies and synchronizes the light waves
CR readers vs. laser film digitizers?
CR:
-photostimulable plate scanned by laser beam
-trapped electrons fall back into their atoms
-lost energy emitted as light
-plate glows
-photomultiplier tubes pick up glowing & convert that light energy into an electrical signal
-signal sent to the computer
laser:
-film scanned by laser beam
-different light intensities penetrate the image
-Bundle of optical fibers that lead to a photomultiplier tube detect light intensities
What kind of wave is visible light?
Double Transverse
____ waves have the longest wavelength and low-energy radiation
Radiowaves
Are radiowaves ionizing or non-ionizing?
Non-ionizing
Light Waves:
- Visible Spectrum
- Smallest segment of EMS
Microwaves:
- Cook your food
- Occur in space (naturally)
- Very short wavelength RF
Energy and Wavelength are always ___ proportional.
Inversely
Energy goes down, Wavelength goes up
Are x-rays ionizing or non-ionizing?
ionizing!
Gamma Rays have the ___ wavelength, highest ___
Shortest
Highest
What is the only difference between x and gamma rays?
is origins: x-radiation is extranuclear and gamm are nuclear in origin
The entire visible light spectrum is encompassed in a one-volt range from __ to __ volts
2-3 volts
X rays for medical diagnosis range from ___ to ___ volts
25,000 to 150,000
______ is the bending of light as it passes through an interface between two materials
Refraction
______ is the orderly splitting of white light through a prism into its several colors
dispersion
_______ is the random refraction or reflection of light, destructive to any image/signal it might be carrying
diffusion/scattering
______ is the complete stoppage of light penetration
absorption
_______ means passing completely through of light, without any loss of energy or intensity
transmission
_______ is the partial absorption of some of the energy of a single incoming x-ray OR some of the intensity/quantity of x-rays within an x-ray beam
attenuation
What makes radiographic imaging possible?
partial absorption of some of the intensity or quantity of x-rays within an x-ray beam
a ______ image has dark details against a light background
Positive
a ______ image has light details against a dark background
Negative
Conventional x-ray images are (positive/negative) images?
Negative
______ states that as long as light is striking the certain metals, electrons will be emitted from their surface
photoelectric emission
the _____ states that certain metal plates are better able to conduct electricity, as long as light is striking them
photoconductive effect
the _______ states that electrical voltage is generated between some materials as long as light is striking them
photovoltaic effect
who is responsible for finding/explaining photoelectric emission, the photoconductive effect, and the photovoltaic effect?
einstein
the _______ happens when an orbital electron absorbs all of the energy of a light (a photon) and is ejected from the atom
photoelectric effect
what type of experiment was used to describe if light, x-rays, and electrons are particles or waves?
two-slit
is light and are x-rays particles, or waves?
behave like particles, similar to water waves
are electrons particles, or waves?
behave like waves in most experiments
a photon is otherwise known as a _______.
quantum
when talking about the “subatomic” world, what specific parts of an atom would you be referencing?
photons or electrons
an _____ is a substance that cannot be broken down into any simpler substance by ordinary (chemical or mechanical) means
Element
an _____ is the smallest single unit of an element, retaining all of its chemical behaviors
Atom
_____ behavior is the making or breaking of physical connections between atoms in which they “share” components (electrons)
Chemical
each electron orbit/shell are made up of sub-orbitals…. each of which can only accommodate _____ electrons
two
what 3 components are atoms composed of?
Protons
Electrons
Neutons
the _____ explanation of the physical structure of an atom states that….
electrons can only exist at certain energy levels, in prescribed “orbits” at set distances from the nucleus
Bohr
the ______ explanation of the physical structure of an atom, established in 1911, states that….
atoms consist of a dense, positively charged nucleus, surrounded by a “cloud” of negatively charged electrons
Rutherford
what are the 4 electron sub-orbitals?
S (sharp), P (principal), D (diffuse), F (fundamental)
How do you convert eV to joules?
1.602 x 10^-19
