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the form of energy we can see

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

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

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

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

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