Waves
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WAVES. Chapter 12 Physics. Waves transfer what?. ENERGY!!!!. What are the two main types of waves?. MECHANICAL WAVES ELECTROMAGNETIC WAVES. Which type of wave requires a medium?. MECHANICAL WAVES Electromagnetic waves do NOT need a medium. What are 3 examples of Mechanical Waves?.

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WAVES

Chapter 12

Physics


Waves transfer what?

ENERGY!!!!


What are the two main types of waves?

  • MECHANICAL WAVES

  • ELECTROMAGNETIC WAVES


Which type of wave requires a medium?

MECHANICAL WAVES

Electromagnetic waves do NOT

need a medium.


What are 3 examples of Mechanical Waves?

  • Water waves

  • Sound waves

  • Seismic waves


Radio waves

What are some examples ofElectromagnetic Waves?


  • Microwaves


  • Infrared light

  • Visible light

  • Ultraviolet light


  • X-rays

  • Gamma Rays


What are the colors of Visible Light?

  • ROYGBIV


ROYGBIV

  • RED

  • ORANGE

  • YELLOW

  • GREEN

  • BLUE

  • INDIGO

  • VIOLET


Which color is the HIGHEST energy wave?

  • VIOLET


Which color is theLOWEST energy wave?

  • RED


What 3 characteristics doAll Waves have?

  • Amplitude

  • Wavelength

  • Frequency


What does the size of the amplitude of a wave tell us?

  • HIGH AMPLITUDE = HIGH AMOUNTS OF ENERGY

  • LOW AMPLITUDE = LOW AMOUNTS OF ENERGY


What unit do we use to measure Wavelengths in?

  • Meters


What greek letter do we useto represent a wavelength?

  • Lambda 


What are the 3 units we can use for Frequency of a wave?

  • Waves / second

  • Cycles / second

  • 1/s = Hertz (Hz)


Frequency Example Problem

  • A boy standing on a dock counts 20 waves

  • pass by in 5 seconds. What is the frequency

  • of the waves?

f = #waves / time

20 waves / 5 seconds = 4 Hz


Frequency Example Problem #2

  • If the frequency of the waves is increased

  • to 8 Hz, how many waves will pass by the

  • boy in 2 seconds?

f = #waves / time

8 Hz = #waves / 2 seconds

8 Hz x 2 seconds = 16 waves


Name the 2 types of Mechanical waves.

  • TRANSVERSE WAVES

  • LONGITUDINAL WAVES


Which type of wave form crests and troughs?

  • TRANSVERSE


Longitudinal wave do not have crests and troughs, instead they have what?

  • COMPRESSIONS

  • RAREFACTIONS


How does the medium movewhen a longitudinal wave moves through it?

  • The medium vibrates horizontally.


Surface Waves move both horizontally and vertically simultaneously, which produces what kind of movement?

  • Circular


Speed of WavesWhat is the wave equation?

  • V = f 

  • speed = frequency times wavelength


SPEED OF WAVESspeed = frequency x wavelength

v = f x λ

Example #1

A wave on a lake is traveling with a velocity of 8 m/s.

the frequency is 2 Hz. What is the wavelength of

this wave?

8 m/s = 2 Hz xλ

λ = 4 m

Speed of a wave example

http://www.acoustics.salford.ac.uk/schools/teacher/lesson1/lesson1interactive.html


Name the 4 ways waves interact.

  • Reflection

  • Refraction

  • Diffraction

  • Interference


Explain reflection of a wave.

  • Bouncing back of a wave after it strikes a boundary.


Explain Refraction.

  • The change in path of a wave when it moves into a medium of a different density.


REFRACTIONBending of waves due to a change in speed.Short tutorial/animation to watch.http://www.wiley.com/college/strahler/0471480533/animations/ch19_animations/animation2.html


Explain Diffraction.

  • The curving of waves around barriers and ability of waves to spread out in circular pattern after passing through a narrow opening. See picture below.


3. DIFFRACTIONBending of waves around the edge of an obstacle.


What are the 2 types of Interference?

  • Constructive

  • Destructive


Which of the pictures below is an example of Constructive Interference?

The picture on the left is constructive interference.

The picture on the right is destructive interference.


4. INTERFERENCE1.   CONSTRUCTIVE INTERFERENCEWhen waves combine and produce a wave that is greater than either of the waves alone.


2.   DESTRUCTIVE INTERFERENCEWhen waves combine and produce a wave that is less than either wave alone.


Applet Interference by 3 wavessimultaneously.

Constructive interference applet

http://id.mind.net/~zona/mstm/physics/waves/interference/waveInterference1/WaveInterference1.html

Both Constructive/Destructive interference applet

http://id.mind.net/~zona/mstm/physics/waves/interference/waveInterference2/WaveInterference2.html


Nodes and Antinodes are parts of what kind of wave?

  • Standing Wave


NODESStationary points of a standing wave.ANTINODESLoops of a standing wave where maximum oscillation of the medium occurs.


The frequency at which a standing wave occurs is called what?

  • Resonant Frequency

  • Sometimes called Natural Frequency.


STANDING WAVESRESONANT FREQUENCY(or natural frequency)The frequency at which a standing wave occurs.


The End!.


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