-
A change in the magnetic field always induces or creates what?
electric field
-
A change in the electric field always induces or creates what?
magnetic field
-
The changing electric or magnetic fields are repetitive, and do what?
oscillate forming waves
-
What is an electromagnetic wave?
patterns of magentic and electric fields changing
-
What speed do electromagnetic waves travel at?
speed of light
-
Do all waves travel at the same frequency and wavelength?
no
-
What changes as waves form a spectrum and the frequencies and wavelengths change?
physical effects change also
-
What are some examples of the physical effects we manipulate in therapy to treat patients?
- visibility
- heat
- chemical effects
- radio/television transmission
-
What is the electromagnetic spectrum?
graphic representation of the range of wavelength of energy including radiant energy, visible, ultraviolet, and infrared
-
What is the length of one wave made by one oscillation?
wavelength
-
What type of electromagnetic waves have the longest wavelength? (lower frequency)
radiowaves
-
What waves have shorter wavelengths? (higher frequency)
infrared, visible, ultraviolet
-
What has the shortest wavelength and highest frequency of all?
gamma rays
-
What are wavelengths measured in?
angstroms
-
What is frequency?
number of oscillations per second
-
What is frequency measured in?
hertz (Hz)
-
What are hertz?
cycles per second
-
If a wavelength is longer, what is the frequency?
lower frequency
-
If the wavelength is shorter, what is the frequency?
higher frequency
-
What type of wavelength gives the deepest penetration?
longer wavelength
-
What type of frequency gives the deepest penetration?
lower frequency
-
What type of frequency gives superficial penetration?
higher frequency
-
In the electromagnetic spectrum, what waves have the highest frequency?
- 1.cosmic rays
- 2. gamma rays
- 3. x-rays
- 4. ultraviolet
*these are like treble, higher and not as deep
-
What is in the middle of the spectrum?
visible light
- violet - higher frequency
- red - lower frequency
-
What waves on the spectrum have lower frequencies?
- 1. microwaves
- 2. radar
- 3. shortwaves / radiowaves
*like bass, deeper and lower
-
1 Hz equals what?
1 cycle per second
-
Different wavelengths and frequencies form different what?
physical effects
-
What is a medium?
environment energy is going through
-
Radiant energy can be effected by a medium in what 4 ways?
- 1. absorbed (what we want)
- 2. reflected (bounce off body, dont affect tissues)
- 3. refracted (ends up at different angle)
- 4. passes right through (has no affect at all)
-
What law states that electromagnetic waves must be absorbed in order to produce effects?
grotthus draper law
-
What is the cosine law?
maximum absorption is going to occur at a right angle to the surface of the skin
-
What is the inverse square law?
the intensity of the energy is inversely proportional to the distance of the source
- *if distance is greater the intensity is less,
- *if the distance is smaller, the intensity is greater
-
What law states waves change direction sometimes while passing through certain mediums (snells law)?
law of refraction
-
What law states energy that is absorbed is used, but not all the energy is absorbed?
law of absorption
|
|
