WAVE PHENOMENA

Wave Reflection Waves bounce off objects and reflect back the direction they came. With sound waves, this creates an echo.Light and sound both travel in waves. Both can be reflected!

The Law of Reflection uses math to determine the angle a wave (light or sound) will reflect.   

You can witness this law in action using a laser pointer and a mirror

Geometry Attack

If the arrow is a flashlight beam, what is its angle of reflection?

120 °

What is REFRACTION

Why does this straw appear broken at the point it enters the water?

Refraction is the bending of a wave caused by a change in speed as it moves from one medium to another.

Light refraction can make it very difficult to catch fish in water, they are not actually where they appear to you...

What is diffraction?When waves bend around objects

Light waves don't bend around a barrier, but sound waves do. 

Wave Applet

AM vs FM radiosFM radios have a short wavelength

AM radios have a long wavelength

AM radio waves can diffract around large building and mountains, reception is often better with AM.

FM has superior sound quality but a shorter range.

Interference - waves overlap, forming a new wave

Constructive = waves add together, if these are sound waves, the sound becomes louder This is called 

AMPLIFICATION

Interference - waves overlap, forming a new wave

Destructive = one wave counters the other, decreasing loudness

*these waves are said to be OUT OF PHASE

Watch what happens when a bridge is subject to constructive interference from wind: Tacoma Narrows  

Standing Waves - waves are traveling in opposite directions with the same  wavelength and amplitudeThis is difficult to visualize, so lets watch the video of a standing wave being formed in a tank.

How would you describe this wave?

Many instruments rely on standing waves for sound

Ex. Violin, Drum, Flutes  

Standing waves don't seem to go anywhere.... 

Surfing a standing wave

RESONANCE 

All objects have their own natural frequencies of vibration, which depend on size, materials and shapes.  Every bell sounds different

Resonance refers to the vibration of an object as it absorbs energy at its natural frequency

Check out how tuning forks have their own frequencies.

Bridge Resonance

How can the bending of light be used to create invisibility?

http://www.youtube.com/watch?v=tBqKkRlaZj4

Rhymes With Wave1.  If you give blood, you might _____________ a life. 2.  If you text and drive, you might enter an early __________. 3.  Soldiers who fight wars are very _____________. 4.  A bat lives in a _________________ 5.  A sidewalk has been __________ (d)

6.  My friend ______________ me a present. 7.  Sometimes, I _____________ white castle hamburgers.

QUIZ  TIME Quiz Name:         Waves II

(only covers last half of notes)

Match the term to its description.

1.  When waves overlap and either increase or decrease the effect.

2.  When a wave bounces off an object and returns

3. When a wave bends as it travels around an object

4.  When light bends as it changes medium (like going from air to water)

A.  refractionB.  diffractionC.  interferenceD.  reflection

5.  All objects vibrate at a certain frequency, like a tuning fork.  This is called ______________________

6.  Which type of radio would give you better reception if you were traveling in the mountains?

7.  If two waves combine to make a bigger wave, it is called  ______________________. 8.  When you pass light through a water molecule, it separates and creates a __________________

9.  The water molecule serves as a  ___________

10.  What color comes after orange on the rainbow?           ___________________________