Retinoscopy And Refinement Flashcards
The branch of science that describes how rays of light behave and how we can change their behavior to meet patients needs.
Optics
______is the portion of the electromagnetic spectrum that is able to stimulate the photoreceptors of the retina, producing visual sensations
Visible light
What are the 2 types of photoreceptors?
Rods and cones
Photoreceptor found throughout the retina numbering 125 million and primarily responsible for vision in dim light
Rods
Photoreceptor found in macula numbering 6-8 million and is responsible for color vision and sharp central visual acuity in daylight.
Cones
Each wave length of light is the distance from …..
Crest of one wave to that of the next.
_______is the number of wavelengths passing a given point in one second
Frequency
Light travels fastest in a ___
Vacuum
(Approx 3.0x10 to the 8th power or about 186,284 miles per second.
The speed of light decreases when it enters a denser medium such as….
Air, water, or glass
The more dense the medium the_____the speed of light
Slower
Although frequency of light does not change as speed decreases, the wavelength is…..
Shortened
The ratio of the speed of light in a vacuum to the speed of light in a denser medium is _______ for that medium.
The index of refraction
(Refractive index =Index of refraction/speed of light in a specific medium)
A material’s _______ is based on its own inherent properties, and is important in lens design.
Index of refraction
Light rays are a visible portion of the ___
Electromagnetic spectrum
Light with shorter wavelengths has a higher_____than light with a longer wavelength.
Frequency
The higher the light’s frequency, the more…..
Energy it releases
What are some natural light sources?
Most important the sun, lightening, fireflies, forest fires, and others
What type of light source is created by man : incandescent light bulbs, neon tubes, lasers, glow sticks
Artificial light
This light sources is most of what we se, due to selective absorption of light rays when they strike objects
Reflected light
In nature, light rays tend to travel in _____ until they strike an object
Straight lines
The concept of ____ describes whether light will diverge or converge
Vergence
When light rays leave a single source spread out as they travel away from the source, it is called……
Divergence
All natural light is…..
Divergent
When light rays from many sources are brought together to a single focal point
Convergence
Distant light rays (more than 20 feet away) are considered ____
Parallel
When light rays strike and opaque object, the light is ______
Selectively absorbed
If all light is absorbed the object will appear…..
Black
If no light is absorbed object will appear….
White
If only some light is absorbed the colors not absorbed will be …
Reflected
