Waves
4 Types of Waves
•
•
•
•
Transverse
Longitudinal
Circular
Torsion
Transverse waves
A transverse wave is one in which the disturbance is
perpendicular to the direction of travel of the wave.
Examples: Light wave, waves on a guitar string.
Longitudinal Waves
Longitudinal wave is one in which the disturbance is parallel
to the line of travel of the wave.
Example: Sound wave in air is a longitudinal wave.
Circular Water Waves
Sometimes called Surface Water Waves
The motion of particles in
surface water waves are circular.
Circular Wave
Circular
Wave
Torsion Waves
• Particles move in a twisting motion.
Torsion Waves
• Particles move in a
twisting motion.
The Doppler Effect
Pitch sounds higher as truck gets closer to you. (shorter wavelength)
Truck sounds lower as truck moves away. (longer wavelength)
Doppler Effect
Doppler Effect
• http://www.acs.psu.edu/drussell/Demos/do
ppler/doppler.html
• http://www.absorblearning.com/media/atta
chment.action?quick=153&att=2947
Constructive Interference
Louder sound (amplify) when compressions interfere constructively.
Light gets brighter (amplify) when crest interferes with crest
Destructive Interference
Compressions interfere with rarefactions to make sounds quieter.
Crests interfere with a trough to cancel or make a wave smaller.
Noise-canceling headphones utilize
destructive interference
http://bcs.wiley.com/hebcs/Books?action=mininav&bcsId=3138&itemId=0471663158&assetId=
92188&resourceId=7923&newwindow=true
Reflection of Light
Law of Reflection - angle of incidence = angle of reflection.
Ex: If the angle of incidence is 90 degrees the angle of
reflection is _______ degrees.
Reflection
Standing Wave
• Wave appears to be standing still because
the wave is being reflected.
One Standing Wave
Resonance
• An object vibrates
sympathetically and
amplifies the energy
of the wave.
Violin strings would be quiet without the
resonance (amplification) of the violin’s body.
• Some said the Tacoma Narrows Bridge
fell due to the resonance with the wind.
• http://www.youtube.com/watch?v=j-zczJXSxnw
Natural Frequency & Resonance
• Natural Frequency – frequency of an
object when disturbed
• Resonance – objects ability to vibrate by
absorbing energy at its natural frequency
Diffraction
Diffraction – waves bend
around an object
Waves bend more if the object is
smaller than the wavelength.
Diffraction of Sound
Refraction
• When light enters a
new medium it
changes speed and
bends.
• Example: White light in air
goes through a prism (glass)
causing the white light to
refract (bend) and spread out.
•
http://www.youtube.com/watch?v=GKo
MSvmM-s8
Polyanna demonstrating
refraction (1:10 to 1:13)
Refraction
Refraction and Speed of the Wave
The Electromagnetic Spectrum
Radio waves, Microwaves, Infrared waves, Visible Light, Ultraviolet Rays, X-Rays, Gamma Rays
Short Wavelength
Long Wavelength
High Frequency
Low Frequency
High Energy
Low Energy
v  f
Visible Light –Remember ROY G BIV
Red, Orange, Yellow, Green, Blue, Indigo and Violet
Infrared Rays
Visible Light
Ultraviolet Rays
X-Rays
Convex Lens
Also called a
converging lens and
is thicker in the
middle. It makes
light converge or
meet at a focal point.
Concave Lens
• Also called a diverging lens, looks like it is
caving in. It causes light to spread out.