Electromagnetic Radiation Flashcards
What is radiation?
The process by which electromagnetic energy travels from source outward through space at a constant velocity
Radiant energy is a result of high intensity _____ reactions
chemical
What are photons?
Massless radiant energy emissions from the sun
- the energy carrier that composes all electromagnetic radiation
Photons with longer wavelengths have _____ frequencies
Photons with shorter wavelengths have _____ frequencies
Lower
Higher
Wavelength
the distance between the peak of one wave and the peal of the preceding or succeeding wave
Frequency
the number of waves per second
Speed = _____ x _____
Wavelength x Frequency
The longer the wavelength of a wave, the ______ the frequency has to be
lower
What does the energy equation state?
The energy of a photon is directly proportional to its frequency. Therefore electromagnetic radiation with higher frequency also has higher energy.
In what direction does electromagnetic energy travel?
Always in a straight line; however it may be reflected, refracted, absorbed, or transmitted, depending on the material/tissue that they strike
Reflected
rays that rebound off the material
Refracted
a ray that passes from one material to another and changes its path
Absorbed
any photons that are not absorbed by the material will be transmitted to deeper levels
Transmitted
rays passing through a material
What happens to a beam of sunlight that passes through a prism?
The rays are refracted and appear as a distinct band of color called a Spectrum
What type of frequency, wavelength and on what end of the spectrum should a modality be used to heat tissue?
Low-frequency
Long-wavelength radiation
At the low-energy end of the spectrum
Describe the wavelength and frequency of Shortwave Diathermy
What is it typically used for?
- Longer wavelength
- Lower frequency
- Clinically used for deep tissue temperature changes, increased vasodilation and increased blood flow (such as Hip Bursitis)
Describe the wavelength and frequency of microwave Diathermy
What is it typically used for?
- Longer wavelength
- Lower frequency
- Clinically used for deep tissue temperature changes, increased vasodilation, increased blood flow
Describe the wavelength and frequency of Infrared modalities
What is it typically used for?
- Medium wavelength
- Medium frequency
(Just under visible light on the spectrum) - Clinically used for superficial temperature changes, increased vasodilation, increased blood flow
What is laser (visible light) typically used for?
Clinically used for pain modulation and wound healing
Describe the wavelength and frequency of UV light
What is it typically used for?
- Shorter wavelength
- Higher frequency
Clinically used for superficial chemical changes, tanning effects, bactericidal such as Wound Care
The Arndt-Schultz Principle states that…
no reactions or changes can occur in the body tissues if the amount of energy absorbed is insufficient to stimulate the absorbing tissues
The Law of Grotthus-Draper states that…
radiation produces action only through absorption of its energy by the substance affected
The Cosine Law states that…
the smaller the angle between the propagation ray and the right angle, the less the radiation reflected and the greater the radiation absorbed
The Inverse Square Law states that…
the intensity of the radiation striking a particular surface is knows to vary inversely with the square of the distance from the source
Acoustic (sound) energy travels at ____ speed than electromagnetic radiation?
Slower
Acoustic (sound) vibrations have _____ wavelengths than electromagnetic radiation?
shorter
Acoustic vibrations depend on _____ through molecular collisions
conduction
The more dense the transmitting medium the _____ the velocity of travel for acoustic energy
greater
Is US an acoustic vibration or a type of electromagnetic radiation?
A type of acoustic vibration
Which penetrates deeper, US or any type of electromagnetic radiation?
Ultrasound
When should ultrasound be used over electromagnetic radiation?
When you wish to penetrate to deeper tissues
