The Behavior of Waves

Wave Speed

Remember: Waves change speed when they encounter a boundary and enter a new medium

Wave Speed

http://www.nisdtx.org/Page/42568Click on the above link and select the video Wave Speed

Reflection

Reflection- when a wave strikes an object and bounces off of it

All types of waves can be reflected Light, sound, ocean, etc. Used by bats and dolphins

All types of waves can be reflected The angle of incidence of a wave is always

equal to the angle of reflection. http://www.acs.psu.edu/drussell/Demos/reflec

t/reflect.html

Reflection

Normal- an imaginary line perpendicular to the reflective surface

Angle of Incidence- the angle formed by the wave striking the surface and the normal

Angle of Reflection- the angle formed by the reflected wave and the normal

Refraction

Why does an object partially in the water look broken or disconnected?

Refraction- the bending of a wave caused by a change in the speed of the wave as it moves from one medium to another Greater change in speed = more bending of

the wave When a wave moves into a medium that slows

it down, the wave is bent toward normal When a wave moves into a medium that

allows it to speed up, the wave is bent away from normal

Refraction

http://www.ps.missouri.edu/rickspage/refract/refraction.html

http://www.physicsclassroom.com/mmedia/waves/ltm.html

http://www.physicsclassroom.com/mmedia/optics/bp.html

Refraction

Diffraction

Diffraction- an object causes a wave to change direction and spread around or through a barrier

Refraction and diffraction both cause bending, but refraction occurs when waves enter a new medium, while diffraction occurs when waves pass around something while still in the same medium

Diffraction

http://www.walter-fendt.de/ph14e/singleslit.htm

http://www.colorado.edu/physics/2000/schroedinger/two-slit2.html

Diffraction

Resonance

Resonance- the ability of an object to vibrate by absorbing energy at its natural frequency

Breaking a glass with sound- resonance: http://www.teachersdomain.org/resources/lsps07/sci/phys/energy/glassbreak/index.html

Tacoma Narrows Bridge

Click the below link to watch the Tacoma Narrows Bridge Video

http://www.nisdtx.org/Page/42568

Breaking Glass

Click on the link below to watch the Breaking Glass video

http://www.nisdtx.org/Page/42568

Interference

http://www.acoustics.salford.ac.uk/feschools/waves/diffract.htm

Interference- the ability of two or more waves to overlap and combine to form a new wave

Waves pass right through each other and continue to travel in their original directions

A new wave exists only while the two original waves continue to overlap

Constructive interference- waves add together

Destructive interference- wave subtract from each other

Interference- green- resulting wave

Interference

http://id.mind.net/~zona/mstm/physics/waves/interference/intrfrnc.html

Standing Waves

Standing waves- a wave pattern that stays in one place

Forms when waves of equal wavelength and amplitude travel in opposite directions- continuously interfering with each other

Nodes- places where the two waves always cancel each other

http://id.mind.net/~zona/mstm/physics/waves/standingWaves/standingWaves1/StandingWaves1.html

http://www.walter-fendt.de/ph14e/stwaverefl.htm

Doppler Effect

Link on the link below to watch the video about the Big Bang Doppler Effect

http://www.nisdtx.org/Page/42568

Doppler Effect

http://www.youtube.com/watch?v=Tn35SB1_NYI

The change in frequency when there is relative motion between an observer of waves and the source of the waves

Doppler with Sound

The Doppler effect-

Change in frequency due to the source or receiver greater the speed the source, greater the Doppler effect Bug swimming Stationary bug

Blue Shift-increase in frequency Red Shift- Decrease in frequency

Doppler Effect

Blue Shift-increase in frequency Red Shift- Decrease in frequency

Red Shift

Click on the link below to watch the video about Red Shift

http://www.nisdtx.org/Page/42568

Bow waves

V-shaped pattern made by overlapping crest

Shock Waves

Produced by supersonic aircraft, three-dimensional cone shaped

Sonic boom – sharp crack heard when conical shell of compressed air that sweeps behind a supersonic aircraft reaches listeners on the ground below.

Supersonic

Subsonic - slower than the speed of sound Supersonic- faster than the speed of sound