refractive index
(noun)
the ratio of the speed of light in air or vacuum to that in another medium.
Examples of refractive index in the following topics:
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Phase-Contrast Microscopy
- Phase-contrast microscopy visualizes differences in the refractive indexes of different parts of a specimen relative to unaltered light.
- Light that is slightly altered by passing through a different refractive index is allowed to pass through.
- Light passing through cellular structures, such as chromosomes or mitochondria is retarded because they have a higher refractive index than the surrounding medium.
- Elements of lower refractive index advance the wave.
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Refraction and Magnification
- Refraction occurs when light travels through an area of space that has a changing index of refraction.
- The simplest case of refraction occurs when there is an interface between a uniform medium with an index of refraction and another medium with an index of refraction.
- Some media have an index of refraction that varies gradually with position.
- This effect is what is responsible for mirages seen on hot days where the changing index of refraction of the air causes the light rays to bend creating the appearance of specular reflections in the distance (as if on the surface of a pool of water) .
- As the light is reflected off the pencil we see that, due to the different refraction indexes of water and air, the pencil appears to bend in the water.
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Interference Microscopy
- It is thus based on measuring the differences in refractive index upon recombining the two beams.
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Finding Patient Zero and Tracking Diseases
- The index case is identified in epidemiology studies by tracking down the infected patients to try to determine how the disease originated.
- The index or primary case is the initial patient in the population of an epidemiological investigation.
- The index case may indicate the source of the disease, the possible spread, and which reservoir holds the disease in-between outbreaks.
- The index case is the first patient that indicates the existence of an outbreak.
- "Patient Zero" was used to refer to the index case in the spread of HIV in North America.
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Magnification and Resolution
- The extent and magnitude of the diffraction patterns are affected by the wavelength of light (λ), the refractive materials used to manufacture the objective lens, and the numerical aperture (NA) of the objective lens.
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Bacterial Polyesters
- Polyesters are deposited in the form of highly refractive granules in the cells.
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The International Committee on Taxonomy of Viruses
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Vinegar
- It can be used to lower the glycemic index of foods if consumed together with them.
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Antibiotics and Selective Toxicity
- For example, whereas penicillin has a high therapeutic index as it does not generally affect human cells, this is not so for many antibiotics.
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Industrial Production of Antibiotics
- For example, whereas penicillin has a high therapeutic index as it does not generally affect human cells, this is not the case for many antibiotics.