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Wave Basics: Transverse and Longitudinal

compression rarefaction

Transverse

(rope)

Longitudinal

(Slinky, sound)

Wave = Disturbance that propagates with a velocity v (l/T)dependent

on the material through which it travels

propagation

oscillation

oscillation

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Wave Basics: Inverse Square Law

3-D Sphere2-D Circle

Power spread over circumference Power spread over area

*Laser light is different due to coherency and collimation

2p r 4p r2

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Wavelets: Huygens Principle

Wave Fronts

Circular Wave

Wave Sources

Plane WaveAll points = source

of circular (orspherical waves)

http://www.falstad.com/ripple/ Setup: Single Slit; 1 Plane Src, 1 Freq

http://www.falstad.com/ripple/http://www.falstad.com/ripple/

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Superposition of Wavelets

Two sources

Longerl Lowerf

FOR DEMONSTRATION,

http://www.falstad.com/ripple/ Setup: Two sources; 2 Src, 1 Freq.

Two sources

Shorterl Higherf Five sources

To find resultant pattern, add waves algebraically.

http://www.falstad.com/ripple/http://www.falstad.com/ripple/

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Superposition: Same frequency, different phases

FOR DEMONSTRATION, we will do this in Mathematica. You can also

try Example 3 on the web site:

http://webphysics.davidson.edu/Applets/superposition/default.html

In Phase: 0 Out of Phase: 180

f(x,t) = 2.5 * sin[8 *(x - t) - pi]

f(x,t) = 2.5 *sin[8 * (x - t)]f(x,t) = 2.5 * sin[8 *(x - t)]

f(x,t) = 2.5 *sin[8 * (x - t)]

f(x, t) +g(x,t) f(x,t) +g(x,t)

http://webphysics.davidson.edu/Applets/superposition/default.htmlhttp://webphysics.davidson.edu/Applets/superposition/default.html

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Superposition: Different frequencies and phases

FOR DEMONSTRATION, we will do this in Mathematica, or try the site:

http://webphysics.davidson.edu/Applets/superposition/default.html

(Example 3)

l1

l2

l1=1

2l2

or f1=2f

2

http://webphysics.davidson.edu/Applets/superposition/default.htmlhttp://webphysics.davidson.edu/Applets/superposition/default.html

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Superposition: Similar frequencies give BEATS

f1

f2= 1.1f1

Slower Beat Frequency

f1

f2 = 1.2 f1

Faster Beat Frequency

ftone = (f1 +f2 )/2

fbeat = f2f1

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Reflection & Refraction: Ray Diagram

Reflection Refraction

Angle is smaller forslower velocity.

http://lectureonline.cl.msu.edu/

~mmp/kap13/cd372.htm for an

animated explanation

http://lectureonline.cl.msu.edu/~mmp/kap13/cd372.htmhttp://lectureonline.cl.msu.edu/~mmp/kap13/cd372.htmhttp://lectureonline.cl.msu.edu/~mmp/kap13/cd372.htmhttp://lectureonline.cl.msu.edu/~mmp/kap13/cd372.htm

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Reflection: Concave Mirror

Light Source

far from Mirror

Light Sourceat Focus

Light Sourcenear to Mirror

http://webphysics.davidson.ed

u/physlet_resources/optics4/de

fault.html

http://webphysics.davidson.edu/physlet_resources/optics4/default.htmlhttp://webphysics.davidson.edu/physlet_resources/optics4/default.htmlhttp://webphysics.davidson.edu/physlet_resources/optics4/default.htmlhttp://webphysics.davidson.edu/physlet_resources/optics4/default.htmlhttp://webphysics.davidson.edu/physlet_resources/optics4/default.htmlhttp://webphysics.davidson.edu/physlet_resources/optics4/default.html

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Refraction: Bending of Light due to Speed Change

Slower

Faster

Marching Band Analogy

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Refraction: Explanation of Sound Travel at Night

Slower

Faster

http://www.falstad.com/ripple/index.html

Setup: Temperature Gradient 1, 1 Src, 1 Freq., Source in lower left corner

http://www.falstad.com/ripple/index.htmlhttp://www.falstad.com/ripple/index.html

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http://www.falstad.com/ripple/index.html

Setup: Temperature Gradient 1, 1 Src, 1 Freq., Source in lower left corner

Sound Travel at Night Applet Lower is Cooler

Sound Travels slower at lower temperatures

http://www.falstad.com/ripple/index.htmlhttp://www.falstad.com/ripple/index.html

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Diffraction: Bending of Light without Speed Change

http://dev.physicslab.org/asp/applets/javaphysmath/java/slitdiffr/default.asp

Local file

http://dev.physicslab.org/asp/applets/javaphysmath/java/slitdiffr/default.asphttp://dev.physicslab.org/asp/applets/javaphysmath/java/slitdiffr/default.asphttp://dev.physicslab.org/asp/applets/javaphysmath/java/slitdiffr/default.asphttp://dev.physicslab.org/asp/applets/javaphysmath/java/slitdiffr/default.asp

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Doppler Effect

FOR DEMONSTRATION,

http://ephysics.physics.ucla.edu/physlets/edoppler_shift.htm

Velocity = 1/2 of Sound Speed

http://ephysics.physics.ucla.edu/physlets/edoppler_shift.htmhttp://ephysics.physics.ucla.edu/physlets/edoppler_shift.htm

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http://lectureonline.cl.msu.edu/~mmp/applist/doppler/d.htmThis site has an applet that is even easier to use.

http://lectureonline.cl.msu.edu/~mmp/applist/doppler/d.htmhttp://lectureonline.cl.msu.edu/~mmp/applist/doppler/d.htm

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Shock Wave

FOR DEMONSTRATION,

http://ephysics.physics.ucla.edu/physlets/edoppler_shift.htm

Velocity = 3/2 of Sound Speed

http://ephysics.physics.ucla.edu/physlets/edoppler_shift.htmhttp://ephysics.physics.ucla.edu/physlets/edoppler_shift.htm