Electromagnetic waves (LIGHT)
Properties
1. Double Transverse (2 waves moving at right angles)
2. Speed: 186,282 mi/sec
3. Can move through a vacuum
4. Lowest point of a wave is a trough
Frequency: Number of cycles per second
Cycle: Crest followed by a trough
-Second, CPS
1800 CE- Scientists asked: How does light move through a vacuum?
-Their answer: Ether- A massless non-detectable “Jelly” (incorrect)
Around 1900 CE: James Clark Maxwell explains light
-Don’t need Ether to explain
-Light is a force of nature
Move a charged particle (electron) and it will emit a force field into space like a wave
-Called: Theory of electricity and magnetism
Electromagnetic Spectrum (From low to high frequencies)
Radio: Good frequencies for communications (A.m. + P.m.)
Microwaves: Universe filled with microwaves from “big bang”
Heat: Example: Direct warmth from sun
Infrared: Used to “see” first planet outside solar system
Visible Light: ROYGBIV 400-750 trillion hurtz
-Red 400-450
-Orange 450-500
-Yellow 500-550
-Green: 550-600
-Blue 600-650
-Indigo 650-700
-Violet 700-750
Ultraviolet (UV)- Suntan
X-Ray: Produced at sun’s core
Gamma: Highest frequency wave
Luminosity: The process where an electromagnetic wave (light wave) is produced
Heat Object: 600-1000
There are 4 ways to cause luminosity:
1. Heat an object
2. Pass electricity though a gas
3. Chemical reactions
4. Nuclear reactions
Coherent Light: All the light waves are in phase with each other. An analogy would be 100 soldiers marching in step.
LASER (Light Amplification by the Stimulated Emission of Radiation)—A device which produces coherent light.
Reflection: When light bounces to a surface
-The angle of incidence equals the angle of reflection
Frequency Dependence (Color): Why we see colors upon reflection
-Materials (surfaces) will keep some colors and reflect others
Absorption: When light is kept by a surface
Blue is being reflected, red keeps warmer colors
Transmission: Light goes through
Fluorescence: Change in frequency during reflection
Ultraviolent Light: Black light
Doppler Effect: Change in frequency due to … motion
Red Shift: Galaxy moving away
Refraction:
Normal Line: Any line drawn perpendicular to a surface
-If the beam of light foes from s medium of lower density (example: air) to a medium of