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Light interacts with matter in 4 known ways.  It sometimes bounces off matter.  Sometimes it is absorbed by matter.  In some cases it passes through.

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Presentation on theme: "Light interacts with matter in 4 known ways.  It sometimes bounces off matter.  Sometimes it is absorbed by matter.  In some cases it passes through."— Presentation transcript:

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2 Light interacts with matter in 4 known ways.  It sometimes bounces off matter.  Sometimes it is absorbed by matter.  In some cases it passes through the matter.  Most times it bends as it encounters matter. **

3  Light is energy and travels in the form of a wave. We call them electromagnetic waves.  Light travels in straight lines unless another force acts upon it.

4  Waves that carry electrical energy and magnetic energy.  An important characteristic of a wave is it’s wavelength. The wavelength of a wave is the distance between two peaks. It also determines the color of the light.

5 Incandescence  Light given off by an object because it is very hot.  Ex. incandescent light bulb (old style light bulb, very inefficient, 90% heat, 10% light, filament 3000°C)

6  Light given off by an object that has not been heated. Chemiluminescence  is light that is release during chemical reactions  Ex. glow sticks Bioluminescence  Is a form of Chemiluminescence that occurs in living organisms.  Ex. fireflies

7  occurs in a sealed glass tube containing one or more gases.  Electricity travels from one end to the other bumping into particles of gas, giving them energy.  The gases release this energy as light.  Ex. street lights

8  is a form of electric discharge. But these gases emit ultraviolet light.  the walls of the glass tube are covered with a substance called a phosphor.  The ultraviolet light transfers energy to the phosphor, which then releases the energy as light  Ex. lights in the ceiling

9  a representation of the types of electromagnetic waves arranged according to wavelength  The only waves of the electromagnetic spectrum that you can see are those of visible light.  The longest waves of visible light are red and the shortest are violet.

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11 Reflection  the process in which light "bounces off“ the surface of an object and travels in another direction Absorption  the process in which light energy remains in the object that it hits, and the light energy is converted into heat Transmission  the process in which light travels through an object and continues travelling

12 Transparent  A property of an object that allows light to penetrate it, making it possible to see objects from the other side. Translucent  A property of an object that allows light to pass through but scatters it in different directions. Opaque  A property of an object that will not allow any light to penetrate it.

13  The color of opaque objects depends on what light they reflect.  White objects reflect all colors of the visible spectrum.  Black objects absorb all colors of the visible spectrum.  Blue objects absorb all colors except blue.  Some objects reflect mostly one color but a little of some others creating shades of a color.

14  For a transparent or translucent object to have a certain color, it must absorb all other colors of light  It must also transmit and reflect the color that is its particular color.

15 Additive Primary Colors  to add colors, you need sources of colored lights that can reach an observer's eyes.  primary additive colors are red, green and blue  overlapping all 3 produces white

16  overlapping 2 produces secondary colors  secondary additive colors are cyan, magenta and yellow Red + Green = Yellow Red + Blue = Magenta Green + Blue = Cyan *

17 Subtractive Primary Colors  when an object absorbs a color, it removes it from the beam of light or subtracts it  Most of the color we see is the result of subtractive colors.  primary subtractive colors are cyan, magenta and yellow.  overlapping all 3 produces the color black

18  subtracting equal amounts of two of the three subtractive primary colors make secondary colors  secondary subtractive colors are the same as the primary additive colors, Red, Green and Blue White – (Cyan + Magenta) = Blue White – (Cyan + Yellow) = Green White – (Magenta + Yellow) = Red *

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