Therapeutic Use of Light Flashcards
What is an Angstrom?
measurement of a wavelength
What is a nanometer?
measurement of a wavelength (billionths of a meter)
What is the electromagnetic spectrum?
range of all possible frequencies of electromagnetic radiation.
What is the inverse square law?
intensity of the waves from a point source varies inversely with the square of the distance from the source. I = 1/D^2
What is the cosine law?
optimal radiation of a surface occurs when the source of the radiation is at right angles to the irradiated surface.
What are the properties of light?
- Wavelength
- frequency
- reflection
- refraction
- absorption
- Photon
- Coherence
- Divergence
- monochromaticity
What is wavelength?
distance between the beginning and end of a single wave cycle.
Each wavelength of visible light has its own specific color
What is frequency?
- inversely proportional to wavelength
- higher frequencies are absorbed more superficially
- usually measured in Hz equal to one cycle per second
What is reflection?
bouncing back of light or sound waves from a surface that they strike
What is refraction?
Change in direction of a sound or light wave when it passes from one medium of different density to another
What is absorption?
substance’s ability to take in light or radiant energy.
What is a photon?
- light as it travels in bundles.
- unit of energy of a ray of light
What is monochromaticity?
all photons have a single wavelength = one color
What is coherence?
- way the wavelength travels;
- all photons travel in the same phase and direction producing a precise parallel beam of light
What is divergence?
-relative parallelism of the beam, minimal divergence over distance = collimated (parallel) or concentrated beam.
What are the factors that influence radiation intensity?
- the strength of the energy output of the source
- the distance of the irradiated area from the source
- the angle of the rays striking the area
- the size of the irradiated area
What are the sources of UV?
- The sun (heliotherapy)- near ultraviolet
- Hot quartz lamps- mercury vapor arc lamp has 2 tungsten filaments; produces complete UV spectrum
- cold quartz lamps- produces energy in the far or short UV range; primarily used for bacterial effect b/c will produce erythema