light waves
DESCRIPTION
Light Wave NotesTRANSCRIPT
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Ch 16Ch 16
Light WavesLight Waves
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LightLight
We see objects because light is either We see objects because light is either emitted or reflected by the objectemitted or reflected by the object
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LightLight
Light is an electromagnetic wave that the human Light is an electromagnetic wave that the human eye can detecteye can detect
Light has wavelengths that range from 400 nm Light has wavelengths that range from 400 nm (violet) to 700 nm (red)(violet) to 700 nm (red)
The speed of light is 3 EE 8 m/sThe speed of light is 3 EE 8 m/s
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Luminous BodyLuminous Body
Emits light wavesEmits light waves Ex: the sunEx: the sun
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Illuminated BodyIlluminated Body
Reflects light wavesReflects light waves Ex: the moonEx: the moon
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Luminous Flux (P)Luminous Flux (P)
The rate at which light is emitted from a The rate at which light is emitted from a sourcesource
It is measured in lumen (lm)It is measured in lumen (lm)
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Illuminance (E)Illuminance (E)
The amount of light that is reflectedThe amount of light that is reflectedE = E = PP
44ππdd22
Units are lm/mUnits are lm/m22 or lux (lx) or lux (lx)
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Luminous Intensity (I)Luminous Intensity (I)
Luminous flux that falls on one square Luminous flux that falls on one square meter of a sphere one meter in radiusmeter of a sphere one meter in radius
I = I = PP
44ππUnits are candela (cd)Units are candela (cd)
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Types of MaterialsTypes of Materials
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TransparentTransparent
Transmits light Transmits light without distortionwithout distortion
Ex: crystal clear waterEx: crystal clear water
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TranslucentTranslucent
Transmits light but the Transmits light but the image is distortedimage is distorted
Ex: lampshadeEx: lampshade
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OpaqueOpaque
Transmits no light Transmits no light All light is absorbed or All light is absorbed or
reflectedreflected Ex: brickEx: brick
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White LightWhite Light
Produced by adding the colors Produced by adding the colors redred, , blueblue and and greengreen
This is called the additive processThis is called the additive process RedRed, , blueblue and and greengreen are called the primary light are called the primary light
colorscolors
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Mixing Light ColorsMixing Light Colors
RedRed and and GreenGreen = = BlueBlue and and GreenGreen = = RedRed and and BlueBlue = =
YellowYellow CyanCyan MagentaMagenta
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Complementary Light ColorsComplementary Light Colors
YellowYellow and and BlueBlue CyanCyan and and RedRed MagentaMagenta and and GreenGreen
Produce white lightProduce white light
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Dyes and PigmentsDyes and Pigments
Dyes are molecules that dissolve in liquids Dyes are molecules that dissolve in liquids to form colored solutions. They absorb to form colored solutions. They absorb certain wavelengths and reflect others.certain wavelengths and reflect others.
A pigment also absorbs certain A pigment also absorbs certain wavelengths and reflects others, but they wavelengths and reflects others, but they are larger and mix to form suspensions.are larger and mix to form suspensions.
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Dyes and PigmentsDyes and Pigments
The absorption process of light forms colors by The absorption process of light forms colors by the subtractive processthe subtractive process
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Primary PigmentsPrimary PigmentsAbsorb one color from white light and reflect 2 colorsAbsorb one color from white light and reflect 2 colors
YellowYellow absorbs absorbs BlueBlue MagentaMagenta absorbs absorbs
GreenGreen CyanCyan absorbs absorbs RedRed
Reflects Reflects red red and and GreenGreen Reflects Reflects BlueBlue and and RedRed
Reflects Reflects BlueBlue and and GreenGreen
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Secondary PigmentsSecondary PigmentsAbsorb 2 colors from white light and reflect one colorAbsorb 2 colors from white light and reflect one color
RedRed absorbs absorbs GreenGreen and and BlueBlue ( (CyanCyan))
GreenGreen absorbs absorbs RedRed and and BlueBlue ( (MagentaMagenta))
BlueBlue absorbs absorbs RedRed and and GreenGreen ( (yellowyellow))
Reflects Reflects RedRed
Reflects Reflects GreenGreen
Reflects Reflects BlueBlue
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Complementary PigmentsComplementary Pigments
Produce black lightProduce black lightBlack is not a color just the absence of Black is not a color just the absence of
lightlightNo light is being reflectedNo light is being reflectedNote: The primary light colors are the Note: The primary light colors are the
secondary pigments and vice versasecondary pigments and vice versa
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What color would a yellow banana What color would a yellow banana appear if it is hit with green light?appear if it is hit with green light?
Answer:Answer:Green, yellow can reflect red and green, Green, yellow can reflect red and green,
but there is only green light hitting it.but there is only green light hitting it.
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What color would a yellow banana What color would a yellow banana appear if it is hit with blue light?appear if it is hit with blue light?
Answer:Answer:Black, the yellow absorbs blue light so Black, the yellow absorbs blue light so
there is no light to reflectthere is no light to reflect
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What color would a yellow banana What color would a yellow banana appear if it is hit with cyan light?appear if it is hit with cyan light?
Answer:Answer:Green, the yellow absorbs blue lightGreen, the yellow absorbs blue lightCyan – Blue = GreenCyan – Blue = Green
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Polarized LightPolarized Light
Light that only Light that only vibrates in one plane.vibrates in one plane.
Polarized light will Polarized light will only pass through a only pass through a polarized filter if it is polarized filter if it is parallel to the parallel to the vibrating lightvibrating light
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Thin Film InterferenceThin Film Interference
The beautiful colors The beautiful colors are caused when light are caused when light reflects off of 2 reflects off of 2 surfacessurfaces
Example: Oil and Example: Oil and water or the 2 layers water or the 2 layers of a bubbleof a bubble