optics test - 4/22/24 Flashcards
for optics test on april 25; not all topics of test included
what is incandescence?
occurs when objects that are heated to high temperatures emit light. colours change with temp. examples include burning candles.
what type of light emission is produced when electric currents pass through gasses, causing them to glow?
electric discharge; examples include lightning and neon signs
what is fluorescence?
when objects emit light immediately after absorbing ultraviolet light. examples include laundry detergents, highlighter pens, etc…
what is phosphorescence?
when materials absorb ultraviolet (UV) light and emit it over time (ex: glow in the dark objects)
what is chemiluminescence?
Light produced as a result of a chemical reaction without producing heat. (ex: light sticks + glow sticks)
what is bioluminescence?
Chemiluminescence in living organisms (ex: certain bacteria, glow worms, fish)
what is triboluminescence?
light produced from friction with crystals, first observed by francis bacon
what is light-emitting diodes (LEDs)?
electronic devices that emit light when electric currents pass through them, more energy efficient than incadescent bulbs, used in things like traffic lights and christmas lights
what is the cornea?
clear tissue that refracts light; makes it go into eye
what is the lens?
focuses the image that cornea creates by fine tuning it
what are the ciliary muscles?
muscles that assist in the process of focusing the image (lens’ job) – they change the shape of the lens
what is the pupil?
entrance that allows light enter the eye
what is the iris?
controls size of pupil (coloured part of eye)
what is the retina?
screen that images are projected into; located in abck of eye
what is the optic nerve?
sends messages to the brain about what is seen by being the receptors in the retina
what causes vision problems?
refraction
what is myopia?
nearsightedness, caused by more refraction from distant objects, causes focusing of images of nearby objects in front of the retina; causing blur
how to treat: convex lenses
what is hyperopia?
farsightedness, caused by vertically stretched eye shape, focuses images of nearby objects BEHIND retina
types of eye surgeries
LASIK, PRK
procedure:
1. Measurement of cornea’s shape and thickness.
2. Cutting a thin flap of the cornea.
3. Reshaping the cornea with laser.
4. Repositioning the corneal flap.
SALT with plane mirrors?
S - Same size
A - Upright
L - Same distance, behind mirror
T - Virtual
SALT with concave mirrors – beyond 2F?
S - Smaller
A - Inverted
L - Right underneath object
T - Real
SALT with concave mirrors – between 2F and F?
S - Larger
A - Upside down (inverted)
L - Further away from mirror
T - Real
SALT with concave mirrors – directly on F?
no image formed
SALT with concave mirrors – less than F? (closest to mirror)
S - Larger
A - Right side up
L - In front of mirror
T - Virtual
SALT with converging lens?
S - smaller
A - inverted
L - between 2F and F
T - real
applications of lenses: the camera
Cameras capture light from distant objects, forming smaller, real images on film or digital sensors. A converging lens produces an inverted, real image when the object is beyond twice the focal length.
applications of lenses: the movie projector
Projects large, inverted, real images on a screen. Film must be between the focal length and twice the focal length.
applications of lenses: the magnifying glass
Simple converging lens (convex) with object between focal point and lens.
Produces enlarged, virtual image on same side as object.
applications of lenses: the compound microscope
Two converging lenses create two images: one real and one virtual.
Real image formed by objective lens, virtual image seen through eyepiece lens.
what is mirage?
optical illusion caused by the bending of light rays due to temperature variations in the air; creating the illusion of water or objects that aren’t actually there
what is inferior mirage?
Inferior mirage: hot ground, bends light, objects seem lower, illusionary water.
what is superior mirage?
Superior mirage: cool ground, bends light, objects seem higher, illusionary elevation.
