Chapter 14
Waves/Sound
The Nature of Waves
•What is a wave?
•A wave is a repeating disturbance ormovement that transfers energythrough matter or space
Waves transfer energy not matter. The water wavesbelow are carrying energy but are not moving. Wavescan only exist as they have energy to carry.
What are mechanical waves?
Mechanical waves are waves which require a medium. A mediumis a form of matter through which the wave travels (such as water,air, glass, etc.) Waves such as light, x-rays, and other forms ofradiation do not require a medium.
What are the two kinds of mechanical waves?
Transverse Waves
In a transverse wave the matter in the wave movesup and down at a right angle to the direction of thewave
What are mechanical waves?
Mechanical waves are waves which require a medium. A mediumis a form of matter through which the wave travels (such as water,air, glass, etc.) Waves such as light, x-rays, and other forms ofradiation do not require a medium.
What are the two kinds of mechanical waves?
Longitudinal Waves (Compression Waves)
In a longitudinal wave the matter in the wave movesback and forth parallel to the direction of the wave
Example of a transverse wave:
Sound Waves are compressional waves.
Sound travels as vibrations moving through the air as acompressional wave.
Sound travels through air, but travels through othermaterials as well. Whale communicate through longdistances by producing sounds under water.
What are the parts of a wave?
Transverse wave
The crest is the highest pointon a transverse wave. Thetrough is the lowest point on atransverse wave.
The rest position of the waveis called the node or nodalline.
The wavelength is thedistance from one point onthe wave to the nextcorresponding adjacent point.
Compressional
Longitudinal wave
On a compressional wavethe area squeezedtogether is called thecompression. The areasspread out are called therarefaction.
The wavelength is thedistance from the center ofone compression to thecenter of the nextcompression.
What is wavelength?
Wavelength is a measure of distance, so the units forwavelength are always distance units, such as meter,centimeters, millimeters, etc.
What is wave frequency?
Frequency is the number of waves that pass through apoint in one second. The unit for frequency is waves persecond or Hertz (Hz). One Hz = One wave per second.
Wavelength and frequency are inversely related.
The smaller the wavelength, the more times it will passthrough a point in one second. The larger thewavelength, the fewer times it will pass through a pointin one second.
Frequency is the number of waves(vibrations) that pass through a point in onesecond.
Period is the time it takes for one fullwavelength to pass a certain point.
Frequency is waves per second.
Period is seconds per wave.
A wave moving through a medium travels at a certainspeed. This is Wave Speed.
Wave speed is usually measured in meters/second, butmay be measured using other distance units (such ascentimeters per second).
How is Wave Speed calculated?
Wave speed is calculated as the product of a wavesfrequency and wavelength.
Wavelength is represented by the Greek letter lambda(λ) and frequency is represented by (f)
What is the amplitude of a wave?
The amplitude of a wave is directly related to theenergy of a wave.
The amplitude of a compressional wave isdetermined by the closeness of thecompressional waves. The closer thecompressional waves and the farther therarefaction lines.
The amplitude of a transverse wave is determined bythe height of the crest or depth of the trough
What is wave interference?
Waves interfere in one of two ways: ConstructiveInterference and Destructive Interference.
