When light strikes an object, the light can be reflected,
transmitted, absorbed, refracted, diffracted or interfered.
RAYS – Straight line white light waves made up of ROY G BIV
REFLECTION –The bouncing back of a wave when it hits a
barrier. The colors reflected are the colors you see.
TRANSMISSION – Light passing through materials.
ABSORPTION – Light energy is transferred to particles. The
farther the light travels the dimmer it becomes. Colors
absorbed are not seen.
SCATTERING – Interaction of light with matter that causes it
to change direction and spread out. Scattering of white
light makes the sky blue when longer wavelengths hit air
particles and are absorbed. Ex: Diffraction gratings
TRANSPARENT MATERIALS –Light transmits through Ex:
Clear glass, air, plastic Wrap
TRANSLUCENT MATERIALS – Some light is absorbed as it
passes through. Ex: frosted glass, wax paper
The color of a transparent or translucent object is the color
of the light it transmits. White light going through
transparent blue glass looks blue.
OPAQUE MATERIALS –Light is absorbed and cannot see
through it. Ex: Aluminum Foil
The color of an opaque object is the color of the light it
reflects. Apples reflects red light.
PRIMARY COLORS of LIGHT– Red, blue & green combine to
make white light.
When combined in equal amounts, the three primary
colors of light produce white light.
SECONDARY COLORS of LIGHT–2 primary colors of light in
equal amounts:
Cyan (blue + green)
Magenta (blue + red)
Yellow (green + red)
COMPLEMENTARY COLORS of LIGHT – Any two colors that
combine to form white light Ex: Cyan + red
PIGMENTS – Paints absorb colors of light & reflect 1 back to
your eye. More paints mixed absorb more light (darker).
As pigments are added together, fewer colors of light are
reflected & more are absorbed.
MIRRORS
LAW OF REFLECTION –The angle that light hits an object is equal
to the angle that light bounces off that object. Drawing: (txt pg 74)
Two types of Reflection
1. REGULAR REFLECTION – When rays of light hit a smooth
surface & are reflected at the same angle. Ex: Mirror
2. DIFFUSE REFLECTION – When rays of light hit a bumpy or
uneven surface & reflected @ different angles. Ex: river
Three types of Mirrors
1. PLANE – A flat sheet of glass that has silver coating on one
side. It produces a virtual image that is upright, same size,
but reversed L to R. DRAWING: (Pg 99)
2. CONVEX –Surface curves outward. Outside of spoon. Makes
smaller images of large areas, used for security, side
mirrors on cars. DRAWING: (Pg 101, Fig6)
3.
CONCAVE –Surface curves inward. Inside of spoon. Rays
focus together in a powerful beam. Used in car headlights
and flashlight. DRAWING: (txt pg 101 Fig5)
LENS
CONCAVE LENS: Thinner in the center than at the edges. Ex:
microscopes, telescopes & eyeglasses
Drawing:
CONVEX LENS: Thicker in the center than at the edges. Ex:
magnifying glasses, eyeglasses & camera lenses
Drawing:
THE EYE
CORNEA –Clear covering over the eye
PUPIL – An opening through which light enters the inside of
the eye. In dim light becomes larger, and in bright light
becomes smaller.
IRIS – Colored ring of muscle that contracts and expand to
change the size of the pupil.
RETINA – Layer of rod and cone cells that line the back
inside of the eye.
RODS – Cells that respond to small amounts of light (white
& black).
CONES – Cells that respond to color.
OPTIC NERVE – Short, thick cord that receives signals from
the rods and cones & sends them to the brain.
LENS – Curved encapsulated fluid that refracts light to the
retina.
NEARSIGHTED – Can see clearly close-up, but objects at a
distance are blurred.
Lens used to correct nearsighted: concave
FARSIGHTED – Can see distant objects clearly, but nearby
objects appear blurry.
Lens used to correct farsighted: convex