interference sound light doppler

8/14/2019 Interference Sound Light Doppler

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Interference


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Interference: The Basics

Waves can interfere with each other.

There are two different types of

interference:

Constructive

Destructive


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Constructive Interference

Makes effects greater

For Transverse Waves:

A crest will interfere with another crest

constructively to produce a larger crest and

a trough will interfere to produce a larger

trough For Longitudinal/Comressional Waves:

Compressions interfere with compressions

Rarefactions interfere with rarefactions


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Destructive Interference

Lessens the effects

For Transverse Waves

A crest will interfere with a trough to lessen

or cancel the displacement of each.

For Longitudinal/Compressional Waves

Compressions will interfere with

rarefactions to lessen or cancel the

displacement of each.


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Sound Waves


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Sound Waves

Sound is a longitudinal/compressional

wave.

Sound requires a medium.

Sound can be produced by vibrating

objects.


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Sound Waves (cont.)

Sound waves reflect. Sound produces echoes when it bounces

off hard surfaces. Sound waves interfere.

Destructive interference makes soundsquieter. Constructive interference makes

sounds louder. Sound waves reflect in tubes of some

musical instruments.


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Light Waves


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Light Waves

Light waves reflect!

The Law of Reflection says the angle of

incidence is equal to the angle of reflection. The angle of incidence is the angle betweenthe incident ray and a line perpendicular tothe surface.

The angle of reflection is the angle betweenthe reflected ray and a line perpendicular tothe surface.


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Law of Reflection


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Mirrors

Light waves reflect inplain mirrors

The image appears asfar behind the mirror asthe object is in front of it

The image and the object

appear to be the samesize

The image is upright


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Light Can Diffract

Diffraction is the bending of a wave

around a barrier or around the edges of

an opening. Waves with a longer wavelength diffract

more readily

When light waves diffract different lightpatterns can be observed


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Diffraction Grating


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Light Can Interfere

Light can interfere constructively and

destructively to produce a color pattern

Light can reflect off the bottom and topsurfaces like oil on water to produce a

color pattern


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Light can Refract

Waves refract when they change

direction upon entering another medium

in which the waves travel at differentspeeds

Light refracts when it enters a different

medium at an angle other thanperpendicular and changes speed


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Refraction


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Light Entering/Leaving a Prism

Light slows down when it

enters a prism and bends

down when it strikes it atan angle

When light exits the prism

it speeds back up andbends down again


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White Light and a Prism

When white light entersanother medium such as

a prism the colors mayspread out. This isbecause the violet endof the spectrum slows

down more than the redend and therefore bendsmore.


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Lenses

Lenses

can be

concaveor convex


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Doppler Effect


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The Doppler Effect

The Doppler Effect is an apparent

frequency shift due to the relative

motion of an observer and a wavesource.

A Doppler shift occurs when a wave

source is moving towards an observeror away from an observer.


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Doppler Effect


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The Doppler Effect

As a wave sourceapproaches an observer,the observer perceives ahigher frequency than thesource is producing.Wavelengths are shorterand the frequency is

higher in front of amoving source.


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