Light Electromagnetic Waves

Ray Model

Speed of Light 220,000,000m/s

Speed of Light (c) c = 3.00 X 10 8 m/s (186,000mi/s) c = λf v = λf

Homework 16-1 PP: 1-5 Pg: 376 Ques: 1-4 Pg: 389 Probs: Pg:390 Due: 3/25/03

Sources of Light A Luminous body emits light waves!

Sources of Light An Illuminated body emits light waves!

Luminous Flux (P) The rate at which visible light is emitted form a source. Lumen: unit for luminous flux.

Illuminance (E) The illumination of a surface lumens/square meter lm/m 2 or lux lx

Inverse-Square Relationship E  1/d 2

Luminous Intensity (candela cd) Some light are measure in candela or candle power Luminance Flux 4π P4πP4π =

Illuminate a Surface E = P 4π d 2 E: Illuminance P: Luminous Flux

Homework 16-2 PP: 6-11 Section Review Page: 381 Due: 3/27/03

Light and Color

Visible Radiation(light): Wavelength between 0.7 and 0.4  m. Optics The study of light and its uses. ROYGBIV Red, Orange, Yellow, Green, Blue, Indigo, Violet

Light and Color Transparent Material that passes or transmits light.

Opaque Material that adsorbs light. No light will pass through.

Translucent Materials that light will shine through, but you cannot see clearly through it.

Primary Colors (light) Additive Colors RedGreenBlue

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Primary Additive Colors

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Pigments A colored material that absorbs certain colors and transmits or reflects others. Pigment are suspensions. Example: Paint

Dye A pigment that dissolves in a liquid to form a colored solution.

Primary Pigment Colors: Subtractive Colors Yellow CyanMagenta

Subtractive Colors White Blue Absorbs: Red Green WhiteRed Absorbs: Blue Green WhiteGreen Absorbs: Blue Red

Primary Subtractive Colors Pigments that absorbs one primary light color and reflects the other two.

Primary Subtractive Colors WhiteBlue Absorbs: Red Green Cyan

Primary Subtractive Colors White Red Absorbs: Blue Green Yellow

Primary Subtractive Colors White Red Absorbs: Green Blue Magenta

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Complementary Colors Yellow Blue Magenta Green Cyan Red

Thin-Film Interference } λ/4 Red 3λ/4 5λ/4 Constructive Interference

Polarization of Light

Color Blindness The color receptors in the eyes (cones) do not function correctly.

 Inherited Condition  8% of Men  ½% of women Ability to distinguish between colors. Primarily red and green. Green cones are deficient.

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Homework 16-3 Review 16-2 Wrap Up Page: 388 Problems: odd Page: 390 Due: 3/31/03

Homework 4-22 Section 19-2 Wrap Up Page: 541 Worksheet Due 5/29/01

Battle of the Bulbs Incandescent Light Light produced by a thin wire called a filament.

Fluorescent Light Light produced the collision of electrons. These collisions produce UV radiation, which is absorbed by the coating around the bulb. UV is converted into visible light.

Fluorescent Light Bulb Pin Electrode Mercury Lead-in Wire Gas Phosphorescent Coating

e Phosphorescent Coating Ultra-Violet Radiation Electron and Molecule Collide White Light

Homework 4-23 Section 19-3 Wrap Up Page: 545 Worksheet Due 6/1/01

Wave Properties of Light Reflection Reflection occurs when a wave strikes an object and bounces off.

Reflection i r i:angle of incidencer:angle of reflection i = r

Refraction The bending of waves. When waves go from one material to another it changes speed. This will cause the light to bend.

Refraction Air Glass

Refraction Prism

The amount that light is diffracted depends on its wavelength. Shorter wavelengths are bent more than longer wavelengths. Violet is bent more than Red!!!

Diffraction The bending of a wave as it passes through an opening or around the edge of an object.

Interference Interference occurs when two or more waves come together. When two crests or two troughs come together we get a bright line. When a crest and a trough come together we get a dark line.

Constructive Interference

Destructive Interference

Diffraction Grating

Homework 4-24 Section 19-4 Wrap Up Page: 550 Voc. Page: 553 Due 6/5/01

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Homework 4-25 Checking Concepts Page: 554 Worksheet Due 6/6/01 Test: 6/8/01

Homework 4-26 Review Page: Due: 6/7/01 Test: 6/8/01