Chapter 5 - Electromagnetic Waves Flashcards
What are the 2 types of waves, and in which direction does each displace the medium?
Book
- transverse (perpendicular)
- longitudinal / compressional (parallel)
What are the 4 measurable characteristics of waves?
Book
- Speed
- Amplitude
- Wavelength
- Frequency
What is the maximum displacement of a medium from its equilibrium position called?
Book
AMPLITUDE
(intensity/strength)
What happens to amplitude as waves spread out from their source?
Book
It diminishes following the INVERSE SQUARE LAW
What is the distance between two points at the same interval of a wave called? (trough-trough, crest-crest etc.)
Book
WAVELENGTH
What is one completion of the wave form before it repeats itself called?
Book
A CYCLE
A cycle consists of 1 positive and 1 negative …
Book
PULSE
What is the number of cycles that passes by a given point in 1 second called?
Book
FREQUENCY
What is the wave formula?
Book
v = fλ
velocity(m/s) = frequency(Hz) x wavelength(m)
What is the electromagnetic wave formula?
Book
c = fλ
the speed of light(m/s) = frequency(Hz) x wavelength(m)
What is the speed of light?
Book
3×10^8 m/s
What is the planck formula?
Book
E=hf
What is the value for planck’s constant?
Book
4.15 x 10^-15 volt-seconds (book)
6.626 x 10^-34 J/s (powerpoint)
What is the factor for conversion of voltage to wavelength?
Book
kV = 12.4 / λ
λ = 12.4 / kV
How does the fact that frequency and wavelength are inversely proportional allow us to adapt Planck’s formula?
Book
E= h / λ
λ = h/ E
What is the type of movement of a particle that generates a magnetic field even when the particle may appear stationary
Book
SPIN
If the wavelength of a homogeneous beam of x-rays was reduced to one-half the original wavelength, exactly how would the number of waves striking you per second change?
Review
IF THE WAVELENGTH IS HALVED, THE FREQUENCY IS DOUBLED
The source of electromagnetic waves is a vibrating or oscillating
Review
ELECTRICAL CHARGE
Which electromagnetic radiation has an energy of 2 to 3 volts?
Review
VISIBLE LIGHT
Which electromagnetic radiation has a wavelength about the width of your smallest finger nail?
Review
MICROWAVES
A body tissue which allows most x-rays to penetrate through it is described in one word as:
Review
RADIOLUCENT
Sonography (ultrasound) images are made possible because when the sound waves reach an interface, they ____, a characteristic which x-rays do not share.
Review
REFLECT AS AN ECHO
What are the three required components for every laser?
Review
- MEDIUM
- POWER/PUMPING SOURCE
- RESONANT CAVITY
The electrical wave and the magnetic wave components of an x-ray are always ____ to each other.
Review
PERPENDICULAR
What two terms describe the random refraction and reflection which ultrasound waves undergo when they encounter an air pocket?
Review
DIFFUSION/SCATTERING
Experiments confirm that electrons have a wave function because two beams of electrons can ____ with each other
Review
INTERFERE
Visible light behaves like ____ in most circumstances, whereas x-rays behave like ____ in most circumstances.
Review
WAVES / PARTICLES
What are the two types of radiation?
Powerpoint
- electromagnetic
- particulate
What is electromagnetic radiation?
Powerpoint
An electric and magnetic disturbance traveling through space at the speed of light
Describe Wave-Particle Duality
Quiz
Wave-particle duality states that while all energies within the electromagnetic spectrum are waveforms, at high enough energies they can also act as particles
Who is James Maxwell and what did he do?
Powerpoint
developed EM theory - all EM radiation:
- has no mass
- travels at the speed of light
- carries energy in waves as disturbances in space
List the different types of EM radiation from low energy to high energy
Powerpoint
- RADIO WAVES
- MICROWAVES
- INFRARED
- VISIBLE LIGHT
- ULTRAVIOLET
- X-RAYS
- GAMMA RAYS
What is the difference between mechanical and EM energy?
Powerpoint
mechanical energy requires a medium to travel - EM can travel through a vacuum
Long wavelengths have ____ frequency and energy
Powerpoint
LOW
Short wavelengths have ____ frequency and energy
Powerpoint
HIGH
What is the inverse square law?
Powerpoint
intensity of EM radiation diminishes over distance by a factor of the square of the distance from the source
I1/I2 = (d2)^2/(d1)^2
What is half-life?
Powerpoint
the time it takes for one-half of the atoms in a radioactive element to decay
What are alpha particles
Powerpoint
- 2 protons + 2 neutrons
- easily pick up electrons to make helium atoms
- dangerous if inhaled
What are beta particles?
Powerpoint
- neutron decays into a proton and a beta particle (-1 charge like an electron)
- bonds with other atoms to reach stability
What is natural frequency?
Book
resonant frequency to which a specific substance is “tuned”
How does MRI work?
Book
- bursts or radio waves are set to a frequency that resonates with hydrogen atoms
- hydrogen atoms in tissues are knocked over, then reset and send a return signal which is picked up by a receiver and interpreted by computers
What frequency is defined as ultra-sound?
Book
over 20,000 Hz
What is the law of reflection and do x-rays follow it?
Book
when light encounters the surface of a mirror, it will reverse direction such that the angle of reflection is equal to the angle of incidence
X-RAYS DO NOT FOLLOW THIS LAW
What does attenuated mean?
Book
partially absorbed
At what point radiation becomes ionizing. Know the definition of ionizing
Study Guide
