36 terms

Grade 8 - Light and Optical Systems

the form of energy we can see http://farm4.static.flickr.com/3234/3100836074_829fc1105a.jpg
Natural Light Source
non-human made source of light, ex. sun, fire, stars, sparks, jellyfish, lightning
Artificial Light Source
a human made source of light, ex. light bulb, lasers, glow sticks, matches
the transfer of radiant energy, such as light
Radiant Energy
energy transferred or emitted as waves or rays in all directions
giving off its own light
a substance that does not give off its own light
Chemical reactions inside living things bodies provide energy for light Chemical reactions inside body - energy for light
Ray Model of Light
a model that represents light as a straight line, or ray, indicating the path of a beam of light.
a single line or narrow beam of light that originates from a light source
Ray Diagram
a representation of the path of light based on the observations that light travels in straight lines
Transparent Materials
Allow all light to pass through, ex. glass, plastic, saran wrap, air, water
Translucent Materials
You can see light but not images ex. paper, some types of glass and plastic
Opaque Materials
Totally blocks light (prevents any from coming through,) ex. book, desk, me
The process in which light strikes a surface and bounces back off that surface
Incidental Ray
The ray that comes from a light source and strikes the object
Reflected Ray
The ray that bounces off the surface
Normal Line
imaginary line drawn perpendicular to the surface of a mirror or any surface
Angle of Incidence
angle between the incident ray and the normal
Angle of Reflection
angle between the reflected ray and the normal
Plane Mirror
a mirror having a flat surface
Law of Reflection
the angle of incidence is equal to the angle of reflection
Convex Mirror
a mirror with a surface that curves outward like a helium-filled party balloon ex. stores and buses to see a wider picture http://farm2.static.flickr.com/1272/1176679797_5163378be4.jpg
Concave Mirror
a mirror with a surface that curves inward like the inside of a shiny bowl ex. make-up mirrors, side-view mirrors on cars to enlarge an image http://farm3.static.flickr.com/2117/2287441388_b21fb74878.jpg
Uses of Reflection
reflectors on cars and bikes, pool players, measure distance to planets
the bending of light when it travels from 1 medium to another http://farm4.static.flickr.com/3525/3203435803_35157186c3.jpg
Angle of Refraction
the angle between the normal and the refracted ray
Energy transformation; rough, dark, opaque surfaces; some light is reflected
bounces off; smooth and shiny: some light absorbed
travels in new direction; different, transparent medium; some light is reflected
Double Concave Lens
thinner and flatter in the middle than the edges
Double Convex Lens
thicker in the middle - the light comes together at a focal point
Convex Lens with a Small Curve
makes the parallel rays converge earlier
Convex Lens with a Large Curve
makes the parallel rays converge later
Far-sighted Vision
image falls behind the retina (eye has a shorter shape than a normal eye) a convex lens allows image to fall on the retina - shortens rays
Near sighted vision
image falls before retina, a concave lens will allow image to fall on retina