Light and Optics Topics Unit Final Flashcards
What is a crest?
Highest parts of a wave.
What is a trough?
lowest parts of a wave.
What is the wavelength?
Distance from crest to crest.
What is the amplitude?
Height of the crest or dept of the trough from rest position.
What is frequency?
rate at which the crest and trough move up and down.
How to calculate speed?
Frequency × Wavelength = Speed
What is the Electromagnetic spectrum?
Refers to the whole range of wavelengths of visible and invisible electromagnetic radiation.
What is the Electromagnetic radiation?
All forms of radiant energy; visible light, infrared light, etc.
What are microwaves?
They have the shortest wavelength and highest frequencies of all radio waves. Have 3 characteristics that allow them to be used in cooking:
1) Microwaves are reflected by metal
2) Microwaves pass through glass, paper, plastic, etc
3) Microwaves are absorbed by foods
What are Radio waves?
You can get radio waves by stretching infrared waves. They have a lower wavelength and a lower frequency than visible light.
What is Infrared Radiation?
Red light (wavelength 700 nm) stretched out to 100nm becomes heat radiation or infrared radiation. Invisible to the eye but can be felt with skin. Anything warmer than it’s surroundings emit infrared rays.
What is Ultraviolet Radiation?
Violet part of the visible spectrum. Wavelength of about 200nm. Very energetic. Causes tanning and can do irreparable damage.
What is X-ray?
Shorter wavelengths, higher frequencies. Pass through tissue, skin, muscle, and absorbed by bones. Stays in bone and builds up overtime so you need protection.
What is gamma ray?
Shortest wavelength and highest frequency in electromagnetic spectrum. Result from nuclear reactions. Can kill cells.
Where do natural light sources come from?
The radiation given off by the sun.
Where do artificial light sources come from?
use filaments that uses electricity or halogen gas to glow, or an electronic device that emits light. `
What is incandescent light?
Caused by electrical energy passing through a filament.
What is florescent light?
Caused by electricity passing through a gas.
What is LED?
Light emitting diodes. Light sources that don’t have filaments that burn or get much hot.
What is phosphorescence?
“Glow in the dark” objects. Able to store light when present and release it in the dark.
What is Bioluminescence?
Occurs when living organisms produce their own light from within their bodies. Usually found in organisms that live in the dark. Used to attract prey or scare off predators.
What are Photophores?
Specialized cells of bioluminescent animals.
What is Chemiluminescence?
Light produced by a result of chemical reactions.
What are primary colors?
Red, Blue, Green
What are secondary colors?
Cyan, magenta, yellow
What do you get if you mix intensities of all three primary colors?
White light
What is the theory of color addition?
mixing of three primary colors of light to produce many different colors of light.
What is the pupil?
The black part of an eye; opening in the eye that lets in light.
What is the iris?
The colored part of an eye; the band of muscle in the eye that controls the size of the pupil and the amount of light entering the eye.
What is the sclera?
White part of eye; fibrous protective outer layer of eye.
What is the cornea?
clear covering on the pupil and iris that helps refract light.
What is the lens?
transparent, biconvex structure that works with the cornea to refract and focus light.
What is the ciliary muscle?
Smooth muscle that controls the thickness of the lens.
What is the virtuous humor?
clear, jelly like substance that fills the eyeball
What is the retina?
Special lining on the back of the eye; when light hits receptor cells, they send messages to the brain which translates them to an image.
What are rods?
receptors sensitive to low levels of light.
What are cones?
receptors that are sensitive to color; 3 different kinds each sensitive to different colors: red, green, and blue.
What is the macula?
small, sensitive area of retina that gives central vision; located in center of retina and contains fovea.
What is the fovea?
center of macula; gives the sharpest vision.
What is the optic nerve?
bundle of more than a million nerve fibers that carry visual messages from the retina to the brain.
What is the photoreceptor cell?
Light sensitive cells found in the retina of the eye; 2 types: rods and cones.
What is Myopia?
An eye is too long so the image forms in front of the retina; near sightedness; distant objects are hard to see.
What is Hyperopia?
Image forms behind retina; far sightedness; close objects are hard to see.
What is Astigmatism?
Occurs when either the front surface of the eye (cornea) or the lens inside the eye has mismatched curves. Causes blurred vision at all distances.
What are camera eye?
eyes are round and have a cornea, lens, and retina
What are compound eyes?
eyes made up of many smaller units
what are Ommaticlium?
unit of a compound eye; has a lens, focusing cone, and light sensitive cell (plural ommatidia.
What is nocturnal?
animals that are active at night.
what is tapetum lucidum?
A layer nocturnal animals have in their eye which acts like a mirror.
What is the diaphragm in a camera?
controls the aperture and depth of an image.
What is the aperture?
opening of the lens’s diaphragm through which light passes.
What is the shutter?
device through which the lens aperture of a camera is open to admit light and thus expose the film.
What is the film?
chemical emulsion on a plastic substrate that is sensitive to light.
What is a digital image?
picture made up of smaller colored pieces called pixels.
What are pixels?
picture elements.
What is the resolution?
number of pixels per unit area in a digital image.
What is a charged couple device?
Otherwise known as CCD, it is a device that converts light into electrical energy. It is used in digital cameras.
