Properties of Waves

1
Properties of Waves

• Project CLEAR Key ConceptsIPC 9.6
• Electromagnetic Waves
• Parts of a Wave wavelength, frequency,
  rarefactions, compressions, crest and trough
• Reflection, refraction, absorption of waves
• Types of waves transverse and longitudinal or
  compression waves
• Application of electromagnetic waves
• Project CLEAR Key ConceptsIPC 9.31
• Demonstrate wave interaction including
  polarization, reflection, interference, and
  resonance

2
Waves

• Definition
• What is a wave?
• Examples
• Name several types of waves.

• Definition
• Mechanical
• Electromagnetic

3
Transverse and Longitudinal
http//www.physicsclassroom.com/Class/waves/U10L1a
.html
http//www.physicsclassroom.com/Class/waves/U10L1a
.html
4
ConcepTest
The graph shows the displacement, s, of a slinky
as a function of position, x, along the slinky.
The wave is

• a transverse wave
• a longitudinal wave
• either of the above
• none of the above

5
Wavelength, Amplitude
http//www.onr.navy.mil/focus/ocean/motion/waves1.
htm
6
Interference
7
Diffraction

• A change in direction of a wave as it passes
  though an opening or around a barrier
• Diffraction can be used to determine the atomic
  and molecular structure of crystalline solids.

http//www.matter.org.uk/diffraction/introduction/
what_is_diffraction.htm http//micro.magnet.fsu.ed
u/primer/java/diffraction/basicdiffraction/index.h
tml
8
Using Diffraction Patterns to Determine Structure
http//micro.magnet.fsu.edu/optics/lightandcolor/d
iffraction.html
9
Diffraction Conditions
Bragg diffraction
q

d
q
q
d


For constructive
interference,

d
n
2(
sin
)

l

q
10
Discovery Slide
11
Line Diffraction
12
Diffraction by Square Unit Cells
13
Refraction of Light

• What is the speed of light?
• Light moves through materials at different
  speeds.

Refractive Index
14
Refraction of Light

• When light hits the boundary between two
  materials of different n, the light gets
  refracted (appears to bend).
• The angle of refraction depends on
• Angle of incidence
• Refractive index of materials

• Which has the greater value of n?
• Glass
• Water

http//micro.magnet.fsu.edu/primer/lightandcolor/i
ndex.html
15
n Values of Common Materials
16
Websites on Waves

• Reading
• http//www.physicsclassroom.com/Class/waves/wavest
  oc.html
• http//www.colorado.edu/physics/2000/schroedinger/
  index.html (and following)
• Explorations
• http//www.surendranath.org/Applets.html
• http//www.phy.ntnu.edu.tw/java/waveType/waveType.
  html
• http//www.netzmedien.de/software/download/java/in
  terferenz/index.html
• Problems
• http//www.explorelearning.com/index.cfm?methodcR
  esource.dspViewResourceID48CFID729720CFTOKEN
  30846136 (requires shockwave and sound)
• 1) What are the unknown frequencies? How did you
  determine this?
• http//www.falstad.com/ripple/
• 2) Start with Setup Basic. Adjust simulation
  speed, resolution, damping, frequency, and
  brightness until you have a feeling for what they
  all do. What kind of wave is shown (standing,
  traveling, etc.)? Click Add Border. What kind
  of wave is shown? Why?
• 3) Change the setup to Double Slit. Describe in
  words the effect you observe and its origins.
• 4) Change the setup to Beats. Notice the
  pattern of dark bands. What is the origin of this
  effect? What parameter can you adjust to modify
  it, or even remove it? Why does that parameter
  allow you to do this?
• Observe slow medium, refraction, internal
  reflection, and scattering. (No problems
  associated with these.)