Crave the Wave
Tutorial Session
Jason Amsden
20141004
General Wave Characteristics
•Crest- the highest point of a wave. Also called
peak.
•Trough- the lowest point of a wave.
•Rest position- the vertical midpoint of a wave.
•Wavelength- the distance between two crests
or troughs.
•Amplitude- the distance between a crest or
trough and the rest position.
•Frequency- the number of times a wavelength
passes a point in one second = 1/period
•Period- the time a wave takes to complete a
wavelength = 1/frequency
Wavelength = speed / frequency
v

f
Wave types
Transverse: disturbance in a medium
perpendicular to the direction of the
advancing wave
Longitudinal: disturbance in a medium
parallel to the direction of the advancing
wave
http://youtu.be/GQ6xE_UhD48
Wave types
Surface: a combination transverselongitudinal wave, forms near the
surface of some media
•Torsional Waves: disturbance
causes the medium to twist
Wave Phenomena: Sound
Sound is a superposition of many
Longitudinal waves
High pitches have a higher frequency wave than low pitches
Wave Phenomena: Light
• Light is an electromagnetic wave
Wave Phenomena: Superposition
the net response at a given place and time caused by two or more stimuli
is the sum of the responses which would have been caused by each
stimulus individually
Constructive Interference
Destructive Interference
Wave Phenomena: Reflection
• The angle of incidence always equals the angle of
reflection (assuming the media are identical
Wave Phenomena: Refraction
• A wave bends toward the normal
when traversing a boundary
between a less dense and more
dense medium due to a slower
velocity
Snell’s Law
Refraction in a prism: angle of
refraction
http://ultrastudio.org/en/Prism
Prism: Dispersion
The index of refraction is wavelength dependent (larger for smaller wavelengths
Wave phenomena: Doppler effect
• The change in frequency of a wave for an observer
moving relative to the source
Electromagnetic Waves:
Electromagnetic spectrum
Electromagnetic Waves:
Electromagnetic spectrum
Spectroscopy: Primary colors of
light
• Because the eye has receptors for red, green, and blue, video screens
use a combination (using superposition!) of red, blue, and green
emission to enable covering a full spectrum
• Light uses additive colors
Pigment Primary colors
• Pigment color is created
when pigments absorb
certain wavelengths
and reflects others. A
blue shirt absorbs all
colors except blue
which it reflects.
• http://www.pbslearning
media.org/resource/lsp
s07.sci.phys.energy.light
pigment/primarycolors-of-light-andpigments/
Absorption Spectra
measure the absorption of radiation,
as a function of frequency or
wavelength, due to its interaction
with a sample.
Absorption spectroscopy is employed as an
analytical chemistry tool to determine the
presence of a particular substance in a sample
and, in many cases, to quantify the amount of
the substance present.
Absorption spectra in astronomy
Emission Spectra
• The emission spectrum of a chemical element or chemical compound is the
spectrum of frequencies of electromagnetic radiation emitted due to an atom or
molecule making a transition from a high energy state to a lower energy state.
The energy of the emitted photon is equal to the energy difference between the
two states.
In astronomy, the emission spectra of
stars indicates their composition
Seismic Waves
• P-waves- aka primary waves, are longitudinal
waves. They are the first to arrive. They can travel
through liquids.
• S-waves- aka secondary or shear waves, are
transverse waves. They are second to arrive. They
cannot travel through liquids.
• Surface Waves- combinations of P and S waves and
occur on the surface. They are the slowest waves.
• Rayleigh Waves- waves that roll in an ocean-like motion.
• Love Waves- waves that move in side to side,
horizontally. Love waves cause the most damage
Seismic waves
Find the Epicenter:
http://www.cposcience.co
m/home/Portals/2/Media/
post_sale_content/PES/PE
S_Chap_20/SkillandPractic
eSheets/20_1_Finding_an
_Earthquake_Epicenter.pdf