Waves

WavesWaves

The Nature of a WaveThe Nature of a Wave

A wave is a rhythmic disturbance that A wave is a rhythmic disturbance that carries energy through matter and space.carries energy through matter and space.

A wave pulse is a single disturbance that A wave pulse is a single disturbance that travels through a medium.travels through a medium.

A continuous traveling wave is a repeating A continuous traveling wave is a repeating and periodic disturbance which moves and periodic disturbance which moves through a medium.through a medium.

The source of all wave motion is a The source of all wave motion is a

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2.2. harmonic objectharmonic object

3.3. vibrationvibration

4.4. amplitudeamplitude

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Waves are the transfer ofWaves are the transfer of

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2.2. mattermatter

3.3. vibrationsvibrations

4.4. waterwater

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What is a medium?What is a medium?

A medium is a substance or material A medium is a substance or material which carries the wave.which carries the wave.

The wave medium is not the wave and The wave medium is not the wave and doesn’t make the wave; it merely carries doesn’t make the wave; it merely carries or transports the wave from its source to or transports the wave from its source to another location.another location.

A trumpet player is in the band room practicing his A trumpet player is in the band room practicing his music for the half-time show. What is the medium music for the half-time show. What is the medium

which carries the sound wave?which carries the sound wave?

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0% 1.1. The trumpetThe trumpet

2.2. The music he is producingThe music he is producing

3.3. The air in the roomThe air in the room

4.4. There is no mediumThere is no medium

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Types of WavesTypes of Waves

Mechanical wavesMechanical waves Electromagnetic wavesElectromagnetic waves Matter waveMatter wave

Mechanical wavesMechanical waves

Mechanical waves require a material Mechanical waves require a material mediummedium

Newton’s laws govern the motion of Newton’s laws govern the motion of mechanical wavesmechanical waves

The speed of mechanical waves depends The speed of mechanical waves depends on the temperature of the mediumon the temperature of the medium

Examples of mechanical waves include: Examples of mechanical waves include: water waves, sound waves, and waves water waves, sound waves, and waves that travel along a rope or springthat travel along a rope or spring

Electromagnetic wavesElectromagnetic waves

No medium is needed for the motion of No medium is needed for the motion of electromagnetic waveselectromagnetic waves

All electromagnetic waves travel at a All electromagnetic waves travel at a speed of 2.9979 x 10speed of 2.9979 x 1088 m/s in a vacuum. m/s in a vacuum.

The details of electromagnetic waves The details of electromagnetic waves cannot be observed directlycannot be observed directly

Examples of electromagnetic waves Examples of electromagnetic waves include: light waves, radio waves, include: light waves, radio waves, microwaves, and X-raysmicrowaves, and X-rays

Electromagnetic SpectrumElectromagnetic Spectrum

Which of the following electromagnetic Which of the following electromagnetic waves travel the fastest at room temp?waves travel the fastest at room temp?

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2.2. MicrowaveMicrowave

3.3. X-raysX-rays

4.4. None of the aboveNone of the above

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Which of the following is NOT Which of the following is NOT an electromagnetic wave?an electromagnetic wave?

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2.2. SoundSound

3.3. LightLight

4.4. X-faysX-fays

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Matter wavesMatter waves

Electrons and other particles show wave-Electrons and other particles show wave-like behavior under certain conditions.like behavior under certain conditions.

Quantum mechanics is needed to describe Quantum mechanics is needed to describe the properties of matter waves.the properties of matter waves.

The type of wave that does not The type of wave that does not require a medium is a(n)require a medium is a(n)

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2.2. mechanical wavemechanical wave

3.3. matter wavematter wave

4.4. All waves require a mediumAll waves require a medium

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The type of wave that travels at The type of wave that travels at 3.0 x 103.0 x 1088 m/s is a(n) m/s is a(n)

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0% 1.1. electromagnetic waveelectromagnetic wave

2.2. mechanical wavemechanical wave

3.3. matter wavematter wave

4.4. All waves travel at this speedAll waves travel at this speed

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This type of wave is governed by This type of wave is governed by Newton’s laws of motion.Newton’s laws of motion.

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0% 1.1. Electromagnetic waveElectromagnetic wave

2.2. Mechanical waveMechanical wave

3.3. Matter waveMatter wave

4.4. All types of wavesAll types of waves

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The properties of this type of wave are The properties of this type of wave are described by quantum mechanics.described by quantum mechanics.

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0% 1.1. Electromagnetic wavesElectromagnetic waves

2.2. Mechanical wavesMechanical waves

3.3. Matter wavesMatter waves

4.4. All types of waves.All types of waves.

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Sound is an example of this type of Sound is an example of this type of wave.wave.

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2.2. MechanicalMechanical

3.3. MatterMatter

4.4. All of the aboveAll of the above

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Light is an example of this type of Light is an example of this type of wave.wave.

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2.2. MechanicalMechanical

3.3. MatterMatter

4.4. All of the aboveAll of the above

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Types of Mechanical WavesTypes of Mechanical Waves

Transverse wavesTransverse waves Longitudinal or compressional wavesLongitudinal or compressional waves Surface wavesSurface waves

Transverse wavesTransverse waves

A transverse wave causes the particles of A transverse wave causes the particles of the medium to vibrate perpendicularly to the medium to vibrate perpendicularly to the direction of the motion of the wave.the direction of the motion of the wave.

The highest point of a transverse wave is The highest point of a transverse wave is called a crest.called a crest.

The lowest point of a transverse wave is The lowest point of a transverse wave is called a trough.called a trough.

Examples of transverse waves include: Examples of transverse waves include: waves in piano and guitar stringswaves in piano and guitar strings

Transverse WavesTransverse Waves

Longitudinal wavesLongitudinal waves

A longitudinal wave causes the particles of a A longitudinal wave causes the particles of a medium to move parallel to the direction of the medium to move parallel to the direction of the motion of the wave.motion of the wave.

The point in which the medium is compressed The point in which the medium is compressed (pressure is increased) is called the (pressure is increased) is called the compression.compression.

The point in which the pressure in a medium is The point in which the pressure in a medium is lowered is called the rarefaction.lowered is called the rarefaction.

Examples of longitudinal waves include: sound Examples of longitudinal waves include: sound waveswaves

Longitudinal WavesLongitudinal Waves

Surface wavesSurface waves

Surface waves are a mixture of transverse Surface waves are a mixture of transverse and longitudinal wavesand longitudinal waves

The particles in the medium move both The particles in the medium move both parallel and perpendicular to the direction parallel and perpendicular to the direction of the waveof the wave

Examples of surface waves include: water Examples of surface waves include: water at the surface of the oceanat the surface of the ocean

Surface WavesSurface Waves

A sound wave is an example of a A sound wave is an example of a ___ wave.___ wave.

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2.2. transversetransverse

3.3. standingstanding

4.4. constructiveconstructive

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A mechanical wave in which the vibration of the A mechanical wave in which the vibration of the individual particles are perpendicular to the individual particles are perpendicular to the direction of the wave is called a ___ wave.direction of the wave is called a ___ wave.

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2.2. soundsound

3.3. transversetransverse

4.4. compressioncompression

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Measuring a WaveMeasuring a Wave Wavelength (Wavelength (λλ)- The shortest distance between )- The shortest distance between

points where the wave pattern repeats itself. points where the wave pattern repeats itself. (Measured in units of length).(Measured in units of length).

Frequency (f)- The number of complete Frequency (f)- The number of complete vibrations per second measured at a fixed vibrations per second measured at a fixed location. (Measured in hertz-Hz)location. (Measured in hertz-Hz)

Period (T)-The shortest time interval in which the Period (T)-The shortest time interval in which the motion repeats itself (Measured in seconds)motion repeats itself (Measured in seconds)

Amplitude- The maximum displacement from the Amplitude- The maximum displacement from the rest or equilibrium position. A wave with a larger rest or equilibrium position. A wave with a larger amplitude transfers more energy.amplitude transfers more energy.

Measuring a WaveMeasuring a Wave

Relationships between wave Relationships between wave propertiesproperties

Wavelength and frequency are inversely Wavelength and frequency are inversely related. As wavelength increases, related. As wavelength increases, frequency decreases.frequency decreases.

Frequency and period are inversely Frequency and period are inversely related. (f=1/T or T=1/f)related. (f=1/T or T=1/f)

The velocity of a wave is equal to the The velocity of a wave is equal to the distance it can travel in a given time distance it can travel in a given time period. v=d/t or v=period. v=d/t or v=λλ/T or v=/T or v=λλff

The time needed for a wave to The time needed for a wave to make one complete cycle is itsmake one complete cycle is its

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2.2. periodperiod

3.3. wavelengthwavelength

4.4. amplitudeamplitude

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The amplitude of a wave is 1 meter. The amplitude of a wave is 1 meter. The top-to –bottom distance of the The top-to –bottom distance of the

disturbance isdisturbance is

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2.2. 1 m1 m

3.3. 2 m2 m

4.4. None of the aboveNone of the above

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If you double the frequency of a If you double the frequency of a vibrating object, its periodvibrating object, its period

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2.2. halveshalves

3.3. is quarteredis quartered

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During a single period, the distance During a single period, the distance traveled by a wave is traveled by a wave is

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2.2. one wavelengthone wavelength

3.3. two wavelengthstwo wavelengths

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Wave BehaviorWave Behavior

The speed of a wave depends only on the The speed of a wave depends only on the properties of the medium it passes properties of the medium it passes through, not on the wave’s amplitude.through, not on the wave’s amplitude.

For example: the speed of the slinky did For example: the speed of the slinky did not change when you increased the not change when you increased the amplitude-only when you increased the amplitude-only when you increased the length.length.

As the tension of the spring increases, the As the tension of the spring increases, the speed of the wave increases.speed of the wave increases.

Waves at BoundariesWaves at Boundaries The wave that strikes a boundary is called the The wave that strikes a boundary is called the incident incident

wavewave.. The wave that returns after striking a boundary is called The wave that returns after striking a boundary is called

the the reflected wavereflected wave.. If the boundary is fixed (like a rigid wall), the reflected If the boundary is fixed (like a rigid wall), the reflected

wave has the same amplitude as the incident wave but is wave has the same amplitude as the incident wave but is inverted (downward).inverted (downward).

http://www2.biglobe.ne.jp/~norimari/science/JavaEd/e-wave6.html

If the boundary is flexible (like a spring), the reflected If the boundary is flexible (like a spring), the reflected wave is upward (erect) and is only partially reflected wave is upward (erect) and is only partially reflected (amplitude is smaller). Part of the wave is also (amplitude is smaller). Part of the wave is also transmitted.transmitted.

http://paws.kettering.edu/~drussell/Demos/reflect/reflect.html

When a wave encounters a boundary, the When a wave encounters a boundary, the wave that strikes the boundary is called thewave that strikes the boundary is called the

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2.2. reflected wavereflected wave

3.3. refracted waverefracted wave

4.4. normal wavenormal wave

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When a wave encounters a boundary, When a wave encounters a boundary, the wave that returns is called thethe wave that returns is called the

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2.2. reflected wavereflected wave

3.3. refracted waverefracted wave

4.4. normal wavenormal wave

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When a wave is sent down a spring connected to a When a wave is sent down a spring connected to a wall, ___of the energy in the wave is reflected wall, ___of the energy in the wave is reflected

back.back.

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2.2. nonenone

3.3. somesome

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A pulse is sent along a spring that is A pulse is sent along a spring that is attached to the wall. The reflected pulse isattached to the wall. The reflected pulse is

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2.2. inverted with a smaller amplitudeinverted with a smaller amplitude

3.3. upright with equal amplitudeupright with equal amplitude

4.4. upright with a smaller amplitudeupright with a smaller amplitude

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Superposition of WavesSuperposition of Waves

When two waves exist in the same place When two waves exist in the same place in the medium at the same time, each in the medium at the same time, each wave affects the medium independently.wave affects the medium independently.

The displacement of a medium caused by The displacement of a medium caused by two or more waves is the algebraic sum of two or more waves is the algebraic sum of the displacements caused by the the displacements caused by the individual waves. This is called the individual waves. This is called the Principle of Superposition.Principle of Superposition.

InterferenceInterference The result of superposition is called The result of superposition is called

interference.interference. Destructive interferenceDestructive interference occurs when occurs when

waves have equal but opposite amplitudes. waves have equal but opposite amplitudes. When the pulses meet and are in the same When the pulses meet and are in the same

location, the displacement is zero. location, the displacement is zero. This point (which doesn’t move at all) is This point (which doesn’t move at all) is

called the called the nodenode. . The waves pass through each other The waves pass through each other

unchanged.unchanged. http://www2.biglobe.ne.jp/~norimari/science/JavaEd/e-wave3.html

Interference (continued)Interference (continued) Constructive interferenceConstructive interference occurs when the wave occurs when the wave

displacements are in the same direction.displacements are in the same direction. The result is an amplitude that is greater than any of the The result is an amplitude that is greater than any of the

individual waves.individual waves. A large pulse appears at the point where the two waves A large pulse appears at the point where the two waves

meet.meet. This point has the largest displacement and is called the This point has the largest displacement and is called the

antinodeantinode.. The waves pass through each other without changing The waves pass through each other without changing

their shapes or sizes.their shapes or sizes. http://www2.biglobe.ne.jp/~norimari/science/JavaEd/e-wave2.html http://www.sciencejoywagon.com/explrsci/media/interfer.htm

___ occurs when two or more waves move ___ occurs when two or more waves move through a medium at the same time.through a medium at the same time.

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2.2. ReflectionReflection

3.3. InterferenceInterference

4.4. ResonanceResonance

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In destructive interference, a point that In destructive interference, a point that experiences no displacement is called aexperiences no displacement is called a

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2.2. troughtrough

3.3. nodenode

4.4. antinodeantinode

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Standing WavesStanding Waves

A standing wave is a wave that appears to be A standing wave is a wave that appears to be standing still. standing still.

Standing waves result from the interference Standing waves result from the interference between the incident wave and the reflected between the incident wave and the reflected wave.wave.

As the frequency of the vibrations is increased, As the frequency of the vibrations is increased, the number of nodes and antinodes increases. the number of nodes and antinodes increases. (see figure 14-14 on page 389)(see figure 14-14 on page 389)

http://www2.biglobe.ne.jp/~norimari/science/JavaEd/e-wave5.html http://www2.biglobe.ne.jp/~norimari/science/JavaEd/e-wave4.html

Waves in Two DimensionsWaves in Two Dimensions

ReflectionReflection occurs when a wave changes direction occurs when a wave changes direction after striking a barrier.after striking a barrier.

Ray diagrams model the movement of waves. A ray Ray diagrams model the movement of waves. A ray is a line drawn at right angles to the crests of waves.is a line drawn at right angles to the crests of waves.

The incident ray is the ray pointing toward the The incident ray is the ray pointing toward the barrier.barrier.

The reflected ray is the ray pointing away from the The reflected ray is the ray pointing away from the barrier.barrier.

The barrier is represented by a line.The barrier is represented by a line. The normal is a line drawn perpendicular to the The normal is a line drawn perpendicular to the

barrier.barrier.

Ray Diagram of WaveRay Diagram of Wave

Normal

Normal

Angle of incidence

Angle of incidence

Angle of reflection

Angle of reflection

Law of ReflectionLaw of Reflection

The law of reflection states that the angle The law of reflection states that the angle of incidence is equal to the angle of of incidence is equal to the angle of reflection.reflection.

The angle of incidence is the angle The angle of incidence is the angle between the normal and the incident ray.between the normal and the incident ray.

The angle of reflection is the angle The angle of reflection is the angle between the normal and the reflected ray.between the normal and the reflected ray.

RefractionRefraction The change in direction of waves at the boundary The change in direction of waves at the boundary

between two media is called between two media is called refraction.refraction. When crossing a boundary into a different medium, the When crossing a boundary into a different medium, the

wavelength decreases; however, the frequency remains wavelength decreases; however, the frequency remains the same. Because there is a decrease in wavelength, the same. Because there is a decrease in wavelength, the velocity also decreases.the velocity also decreases.

The change in velocity causes a change in direction. The change in velocity causes a change in direction. (see page 391)(see page 391)

RefractionRefraction

DiffractionDiffraction

Diffraction Diffraction is the spreading of waves is the spreading of waves around the edge of a barrier. Diffraction around the edge of a barrier. Diffraction also occurs when waves meet an obstacle also occurs when waves meet an obstacle and bend around it, producing waves and bend around it, producing waves behind it.behind it.

The smaller the wavelength, the less the The smaller the wavelength, the less the diffraction.diffraction.

DiffractionDiffraction

Doppler EffectDoppler Effect

The Doppler effect is the change in the The Doppler effect is the change in the apparent frequency of a wave due to the apparent frequency of a wave due to the motion of either the observer or the source motion of either the observer or the source of the wave.of the wave.

An incident light wave strikes a mirror at a 35An incident light wave strikes a mirror at a 35oo angle with the surface of the mirror. What is the angle with the surface of the mirror. What is the

angle of reflection?angle of reflection?

1.1. 3535oo

2.2. 5555oo

3.3. 6565oo

4.4. 9090oo

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___ refers to the bending of waves as the ___ refers to the bending of waves as the waves pass through different mediums waves pass through different mediums

resulting in a change in speed of the wave.resulting in a change in speed of the wave.

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2.2. reflectionreflection

3.3. refractionrefraction

4.4. interferenceinterference

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___ refers to waves that bend around the edge of ___ refers to waves that bend around the edge of a barrier due to the dragging as the waves move a barrier due to the dragging as the waves move

through the opening.through the opening.

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Rainbows are an example of the Rainbows are an example of the ___ of light.___ of light.

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An echo is an example of the ___ An echo is an example of the ___ of sound.of sound.

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