A wave is
 a disturbance that passes energy in packets
 Each wave is a different packet of energy

Light wave packet
= photon
 Ex-ocean wave, sound waves, light waves

Mediums


Waves travel through
“ stuff ” —a medium
Medium transmits energy by vibration collisions
 Sound waves require a medium…
Bell in a vacuum jar demo
Old Style
Stadium Style

Wave Properties






Crest=

Top of wave
Trough=

Bottom of wave
Amplitude=

Height of wave (pitch)
Wavelength=

Length from crest to crest
Frequency=

# waves / second (how often) in
Hertz
Speed=
 varies with medium

Wavelength, Frequency & Energy

Shorter wavelengths are more frequent and more energized
 Longer wavelengths, less frequent and decreased energy
 Speed=wavelength x frequency
Wave Frequency Animation

B
A
 Which has more energy?
 Longer wavelength?

Higher frequency?

Longitudinal & Transverse Wave Types

Longitudinal = energy moves parallel to direction of wave travel
( move a long )
 alternately compresses and stretches the medium it travels through
 Ex. Sound waves; speed 300m/s

Longitudinal (compression) waves
 Compressions
(crests)-medium is squeezed together
 Rarefractions
(troughs)- medium is stretched out.

Transverse waves
 wave moves up and down OR side to side; perpendicular to the wave ’ s direction of motion

Light is a special transverse wave
 A self propelling wave of electro magnetic radiant energy
Speed of ALL light
(c) = 300,000 km/sec
7.5 times around Earth in 1 second!
8min for sunlight to travel from sun to Earth!

Electrical currents generate magnetic fields
 which in turn generate electric fields

Does NOT need a medium

E lectro M agnetic R adiation Spectrum ( EMR )

The range (Spectrum) = wavelengths, frequencies and energies light comes in

Visible light is the only portion that our eyes detect
IR
R ed
O range
Y ellow
G reen
B lue
I ndigo
V iolet
UR
= Visible white light

X-Ray
UV
Objects generate more than just visible light… IR
-We assign a visible color to each intensity to create an Ultraviolet image
Visible
Radio

Multiple satellites create one mixed image
Chandra-X-ray
Hubble-Visible
Spitzer-IR

The atmosphere blocks some EMR

Prism in Action
Refraction –bending of light

Refraction happens when light changes speed in different density mediums
 Violet light with shorter wavelength refracts more than longer wavelength,
Red as glass slows light
 The differential bending
(refraction) separates white light into the colors

How do we see color?-Reflection/Absorption

Light can be reflected
(bounce off) and absorbed (energizes object atoms)
 Light must reflect off objects and enter our eye
 Reflected color is color we see

Why is it that color?

Wave-Particle Duality

Double Slit Animation
Wave-Particle Duality


Radio is light!
 AM=Amplitude Modulation
 FM=Frequency Modulation

 Mirage = refracted light through air of different densities

STOP HERE

nothingnerdy.wikispaces.com
 White light separated into rainbow spectrum by prism refraction
 Element emission spectra made visible by refraction also

 Type of medium can change the speed of the wave (refract
/bend wave)

Light Color vs Energy