waves waves as energy waves as energy types of waves types of waves parts of a wave parts of a wave...
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WavesWaves as energyTypes of wavesParts of a wave
Movement of wavesProperties of waves
What exactly is a wave?• Definition: A wave is any disturbance that
transmits energy through matter or space• Waves move through matter but they do
not move the matter itself
• Ocean waves• Sound waves• Light waves• Radio waves• Microwaves• Earthquake seismic waves
So how are these waves different?
• Waves can travels through a medium ( ex. water, ground, air)
• Mechanical waves need a medium
• Electromagnetic waves do not need a medium
Types of Waves
• Particles in a transverse wave vibrate in an up and down motion perpendicular to the wave direction.
• Particles in a compressional wave vibrate back and forth in the same direction that the wave travels.
• At the boundary between two media transverse and longitudinal waves can combine to form surface waves.
Longitudinal and Transverse Wave Motion
Animation courtesy of Dr. Dan Russell, Kettering University
Parts of a WaveCrest: the highest point
Trough: the lowest point
Amplitude is the height of a wave is and how much energy it is carrying.
The wavelength is the distance between crests
Properties of Waves
Wave simulator courtesy of National Geographic Website
Compressional Waves
Compression: is an area in a wave where the particles are closer together.
Compressional Waves
Rarefaction is an area in a wave in which the particles are spread further apart.
More Wave Properties
Frequency (f) is the number of waves that pass a point in a given time, and measured in hertz. A period (p) is the inverse of frequency = 1/f
(time for one wave to pass)
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More Wave Properties
The wave speed is measured as distance divided by time. But it can also be calculated by multiplying wavelength by frequency.
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More Wave Movement…• When waves bounce off something is
it called reflection. • A reflected sound wave is called an
echo.• When a wave is bent at an angle as it
passes through a new medium it is called refraction.• When a wave is bent around a barrier or
an opening it is called diffraction
• When an object or wave hits a surface through which it cannot pass, it bounces back.
- Interactions of Waves
Reflection
- Interactions of Waves
Refraction• When a wave enters a new medium
at an angle, one side of the wave changes speed before the other side, causing the wave to bend.
- Interactions of Waves
Diffraction• When a wave moves around a barrier
or through an opening in a barrier, it bends and spreads out.
When Waves Interfere with each other…
• Interference is when two waves overlap. They can overlap and make a larger wave, they can also cancel each other out.
Interference• The interference that
occurs when waves combine to make a wave with a larger amplitude is called constructive interference.
The interference that occurs when waves combine to make a wave with a smaller amplitude is called destructive interference.
- Interactions of Waves
Standing Waves• If the incoming wave and a reflected
wave have just the right frequency, they produce a combined wave that appears to be standing still.
More Wave Properties…
• When the vibrations of one object cause another nearby to vibrate…that is Resonance.
• Some musical instruments use resonance to produce sound, like a marimba.