The electrons within atoms are the sources

of all light

There are four steps that There are four steps that electrons go through to electrons go through to

produce light.produce light.

Light is formed when...Light is formed when...

3. Fall back down,

1. Electrons gain energy,2. Move up an energy level,4. And release that energy

The tiny packet or bundle of light energy that is released

is called a PhotonPhoton

•LIGHT is made up of a stream (like a wave) of photons

THIS IS WHY WE SAY THIS IS WHY WE SAY LIGHT CONTAINS BOTH LIGHT CONTAINS BOTH PROPERTIES OF WAVES PROPERTIES OF WAVES

ANDAND PARTICLES PARTICLES

1. IncandescentIncandescent: light produced by a thin wire filament; energy flows through and light is given off in the form of light and heat.

2. FluorescentFluorescent: bulb filled w/mercury gas at a low pressure.•Electricity flows through, the electrons collide w/ the gas giving off UV radiation.

•PhosphorsPhosphors coat the bulb absorb the UV radiation and giving off the light.

Fluorescent light without phosphors

3. NeonNeon: bulbs that glow and give off a variety of colors, depending on the type of gas it contains

A beam of coherent light

(a single wavelength)

Used in surgery

LLight ight AAmplification of mplification of SStimulated timulated EEmission of mission of

RRadiationadiation

Def. - When waves vibrate along a single plane (sunglasses)Can you see Can you see the turtle???the turtle???

Gives off it’s Gives off it’s ownown light lightEx. – The Ex. – The sun, light sun, light bulbs, and bulbs, and candles are candles are luminous luminous objectsobjects

Reflects light from another source

Moon

All light can pass through

Some of the light can pass through; Ex. – Wax

Paper

Includes materials that absorb or reflect ALL light so that no light is transmitted through

• White light is actually all colors of the visible spectrum

• Prism: an object (usually a piece of glass) that refractsrefracts white lightwhite light and separates the colors based on their different frequencies

•Additive Colors

•When all three are mixed, white light is produced.

Green

Blue

Red

blue and green are absorbed

Apple Apple appearappears reds red

White light White light = = mixture of mixture of colorscolors

Because….redred light is reflected!!

So what determines the So what determines the color of an object?color of an object?

•Subtractive (used in ink & paint)•When all three are mixed, black is produced.

Yellow

Magenta

Cyan

•Color printers use the same principle.•Look closely; there are only 3 colors of dots. •Magenta, Yellow, and Cyan