Mechanical WaveMechanical Wave –– a vibratory a vibratory disturbance that propagates through a disturbance that propagates through a medium.medium. Examples –Examples – sound waves, seismic sound waves, seismic

waveswaves

Medium –Medium – the material (matter) through the material (matter) through which a disturbance travels.which a disturbance travels.

Electromagnetic Wave –Electromagnetic Wave – energy waves energy waves produced by the oscillation or acceleration produced by the oscillation or acceleration of an electric charge. Does not require a of an electric charge. Does not require a medium in order to travel.medium in order to travel. Examples –Examples – light, microwaves, radio light, microwaves, radio

waveswaves

Longitudinal Wave –Longitudinal Wave – a wave in which the a wave in which the motion of the vibratory disturbance is motion of the vibratory disturbance is parallel to the direction of propagation.parallel to the direction of propagation.

Transverse Wave –Transverse Wave – a wave in which the a wave in which the motion of the vibratory disturbance is motion of the vibratory disturbance is perpendicular to the direction of travel.perpendicular to the direction of travel.

Surface waves –Surface waves – waves which have waves which have characteristics of both transverse and characteristics of both transverse and longitudinal waves.longitudinal waves.

Torsional -Torsional - a twisting disturbance a twisting disturbance moving through a medium.moving through a medium.

Wave pulse –Wave pulse – a single bump or a single bump or disturbance. (1/2 wave)disturbance. (1/2 wave)

Cycle –Cycle – one complete wave (vibration).one complete wave (vibration).

Periodic wave –Periodic wave – a series of pulses a series of pulses (waveform)(waveform)

Label the following properties and their appropriate Label the following properties and their appropriate symbols on the diagram below.symbols on the diagram below.

Record the correct amount of each of the Record the correct amount of each of the following properties:following properties:

List all of the possible intervals that List all of the possible intervals that represent ONE wavelength.represent ONE wavelength.

Draw a waveform having an amplitude of Draw a waveform having an amplitude of 2.0 m and a wavelength of 4.0 m.2.0 m and a wavelength of 4.0 m.

Frequency ( Frequency ( ƒƒ ) ) – the number of waves – the number of waves (cycles, complete vibrations) experienced (cycles, complete vibrations) experienced in one second. in one second.

Unit –Unit – Hertz (Hz)Hertz (Hz)

total

# wavesf=

t* Not on Reference Table

Which wave has a higher frequency? Which wave has a higher frequency?

Explain.Explain.

Period ( Period ( TT ) – ) – the time required for one the time required for one complete vibration (wave, cycle) to complete vibration (wave, cycle) to occur. occur.

• Unit -Unit - seconds (seconds (ss))

1T=

f* Not on Reference Table

totaltT =

# waves

For most mechanical waves, both transverse For most mechanical waves, both transverse and longitudinal, the speed depends only on…and longitudinal, the speed depends only on…

The medium through which the waves The medium through which the waves move.move.

Water WavesWater Waves

Sound WavesSound Waves AirAir

Waves on a Waves on a SpringSpring

v = ƒ λ

Determine which of the two springs is more dense Determine which of the two springs is more dense by noticing how the pulse is reflected and by noticing how the pulse is reflected and transmitted after reaching the boundary.transmitted after reaching the boundary.

The wave represents a transverse wave. Various The wave represents a transverse wave. Various locations of the wave are labeled and then locations of the wave are labeled and then

grouped in pairs, as given below.grouped in pairs, as given below.

Interference – Interference – the effect produced by two the effect produced by two or more waves which are passing or more waves which are passing simultaneously through a regionsimultaneously through a region..

Constructive Interference – Constructive Interference – waves waves combining to increase amplitude when combining to increase amplitude when their displacements are in the same their displacements are in the same direction.direction.

Destructive Interference – Destructive Interference – waves waves combining to decrease amplitude when combining to decrease amplitude when their displacements are in opposite their displacements are in opposite directions.directions.

The resultant displacement at any point is The resultant displacement at any point is the algebraic sum of displacements of the the algebraic sum of displacements of the individual wavesindividual waves..

When waves meet, their amplitudes When waves meet, their amplitudes combine.combine.

Watch 1:28 to 2:54 then 4:00 to 4:54

Node – Node – point in a wave which doesnpoint in a wave which doesn’’t move at t move at all.all.

Antinode – Antinode – point in a wave having the largest point in a wave having the largest displacement.displacement.

Determine the following for each diagram below: Determine the following for each diagram below: wavelength, number of nodes and antinodes, and wavelength, number of nodes and antinodes, and frequency (for a given wave speed of 10.0 m/s).frequency (for a given wave speed of 10.0 m/s).

As the frequency of the wave increases, the As the frequency of the wave increases, the number of nodes also increases.number of nodes also increases.

Sound wave – Sound wave – a pressure variation that is a pressure variation that is transmitted through matter.transmitted through matter.

v = 331 m/s

Light – Light – the range of frequencies of the the range of frequencies of the electromagnetic spectrum that can be electromagnetic spectrum that can be detected by the retina of the eye.detected by the retina of the eye.

Speed of Light (Speed of Light (cc) – ) – in a vacuum, light has a in a vacuum, light has a constant speed of 3.00 x 10constant speed of 3.00 x 1088 meters per second meters per second

Light travels slower when passing through Light travels slower when passing through different types of mediums.different types of mediums.

ALL electromagnetic waves travel at 3.00 x 10ALL electromagnetic waves travel at 3.00 x 1088 m/s in a vacuumm/s in a vacuum

Natural Frequency – Natural Frequency – the frequency with the frequency with which an object oscillates in the absence which an object oscillates in the absence of external forcesof external forces

What would happen if the opera singer sang a note at What would happen if the opera singer sang a note at the same natural frequency as the crystal wine glass?the same natural frequency as the crystal wine glass?

Fast forward to 2:12 Fast forward to 15:00

Resonance – Resonance – the increase in amplitude of the increase in amplitude of oscillation of an object when exposed to a oscillation of an object when exposed to a periodic force or wave whose frequency is periodic force or wave whose frequency is very close to the object’s natural frequencyvery close to the object’s natural frequency

Angers Bridge, also called the Basse-Angers Bridge, also called the Basse-Chaîne Bridge.Chaîne Bridge. Soldiers marching caused the bridge to Soldiers marching caused the bridge to

collapse.collapse.

Many of the serious vibration problems in Many of the serious vibration problems in engineering are caused by resonance. engineering are caused by resonance.

If the natural frequency of the car body is the If the natural frequency of the car body is the same as the combustion frequency in the same as the combustion frequency in the engine (at certain speeds), the body might engine (at certain speeds), the body might begin to vibrate or shake roughly.begin to vibrate or shake roughly.

Tacoma Narrows BridgeTacoma Narrows Bridge Washington StateWashington State

• November 1940November 1940

http://www.civeng.carleton.ca/Exhibits/Tacoma_Narrows/http://www.me.utexas.edu/%7Eme179/topics/lessons/case1.html

Nicola TeslaNicola Tesla Resonance DeviceResonance Device

Wheatstone Bridge H.S.Wheatstone Bridge H.S.

Pokemon cartoon Pokemon cartoon triggers seizures triggers seizures in thousands of in thousands of Japanese Japanese children.children.

Microwaves emit radio waves at a Microwaves emit radio waves at a frequency of 2.5 GHz which is the natural frequency of 2.5 GHz which is the natural frequency of water. Due to this fact, the frequency of water. Due to this fact, the radio waves cause liquid molecules to radio waves cause liquid molecules to resonate (vibrate) and heat up.resonate (vibrate) and heat up.

RedshiftRedshift

The light of an object The light of an object moving moving AWAY from AWAY from an observer is shifted an observer is shifted

toward a toward a longer longer wavelengthwavelength, or , or

toward the color toward the color redred..

BlueshiftBlueshift

The light of an object The light of an object moving moving TOWARDTOWARD an an

observer is shifted observer is shifted toward a toward a shorter shorter wavelengthwavelength, or , or

toward the color toward the color blueblue..

Diffraction – Diffraction – is the production of circular is the production of circular waves that spread out from the edge of an waves that spread out from the edge of an obstruction or slit as waves pass by.obstruction or slit as waves pass by.

A change in the wavefrontA change in the wavefront’’s direction results.s direction results.

This is the reason why you can hear This is the reason why you can hear sounds around a corner, but not see the sounds around a corner, but not see the object producing the sound.object producing the sound. Sound λ > Light λSound λ > Light λ

In 1801, Young developed an experiment In 1801, Young developed an experiment that allowed him to that allowed him to

Make a precise measurement of lightMake a precise measurement of light’’s s wavelength using diffraction.wavelength using diffraction.

Provide evidence of the wave nature of Provide evidence of the wave nature of light.light.