Wave PropertiesInterference

Wave PropertiesThere are 6 main properties, or interactions, of waves that occur when a wave comes in contact with another wave , or a boundary.

The 6 Interactions of waves are Interference Diffraction Reflection Refraction Absorption Polarization

InterferenceWhen two or more waves

combine together.

Superposition principle

There are typically many waves in the same system at the same time.

When more than one wave is present, the total oscillation of any point is the sum of the oscillations from each individual wave.

The sound waves and light waves you experience are the superposition (adding up) of thousands of waves with different frequencies and amplitudes.

Your eyes, ears, and brain separate the waves in order to recognize individual sounds and colors.

Constructive InterferenceConstructive interference occurs when waves add up to create a larger amplitude wave.These waves are in-phase with each other.

Constructive Interference

When two waves combine to make a larger wave. (crest & crest) or (trough & trough)

Destructive InterferenceDestructive interference occurs when waves

add up to make a smaller amplitude wave.

These waves are out-of-phase with each other.

Destructive Interference

Two or more waves combine to produce a smaller wave or destroy the wave completely.

(crest & trough)

Check for Understanding!

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Results of Interference of Waves One of the consequences of wave

interference is a phenomenon called resonance.

Resonance is the reinforcing of an object’s natural frequency so that the amplitude increases very quickly.

Can you think of something that you have seen or heard that you believe to be caused by resonance?

Standing Waves A wave that is confined

between boundaries is called a standing wave.

With all waves, resonance and natural frequency are dependent on reflections from boundaries of the system containing the wave.

Resonance occurs when the reflected pulses add together to form a large amplitude pulse.

ResonanceResonance can also occur when one object vibrates another without touching

A sound wave vibrates a snare drumA singer hits a note that shatters a

glassA struck tuning fork causes another

tuning fork of the same frequency to vibrate

The strings of a guitar vibrate from a sound across the room

Resonance

Natural Frequency and Resonance

The natural frequency is sometimes called the resonant frequency because the frequencies are the same when the large amplitudes begin to occur.

Real World Examples:

Chinook Helicopter Ground Resonance Test

The Tacoma-Narrows Bridge is an example of driven oscillations that result in large amplitude oscillations.

Resonance

Today’s Assignment For your grade today, you and your elbow partner

need to find a picture, newspaper article, news report or video of an example of Resonance that I have not already given you.

I will give you 10 minutes to research on your phones or an iPad.

Raise your hand when you are ready to show me and explain your example.

I will come by every group to see what you have done for your grade today!