Light

Coach Dave EdingerJ. C. Booth Middle School

Physical Science (8A)

Speed of light = 300,000,000 m/s

ORabout 187,500 mi/s

electromagnetic wave: a transverse wave that is partly electric and partly magnetic

visible light: light you can see

ROY G BIV

Most materials absorb some frequencies and reflect the rest.

The color you see is the light that is reflected.

Ex. If an object reflects red light but

absorbs all other frequencies, then the object appears

red.

If an object absorbs all

frequencies of light, then it

appears black.

If an object reflects all frequencies, then it appears

white.

An object can only reflect

frequencies that are present in

the illuminating light.

Ex. Incandescent light is richer in frequencies

toward the lower end of the spectrum, therefore,

objects appear to be more red

Ex. Fluorescent lights tend to be richer in frequencies toward the higher end of the spectrum, therefore,

objects appear more blue.

Together, all of the colors of the visible spectrum make white light (ex. sunlight)

White light also results from the

combination of red, green and blue.

What happens when certain waves of visible light are

combined?

primary colors of light: red, green and blue

red + green = yellow

red + blue = magenta

green + blue = cyan

Mixing pigment is different than mixing light!!!

As pigments are added together, fewer colors of

light are reflected and more are

absorbed.

primary colors of pigment: cyan, yellow, magenta

Reflection: the bouncing back of a wave

ex. mirrors

Refraction: the bending of waves as they enter a new medium

ex. eyeglasses, prisms