Section 12­3 notes.notebook
March 08, 2012
A wave is the motion of a disturbance. For example, a rock thrown into a pond produces waves from the point of disturbance.
Medium ­ is the material through which a disturbance travels. (water)
Mechanical Wave ­ is a wave that through a deformable, elastic medium. In other words material that the waves travel through, water or air. Not all waves require a medium such as electromagnetic waves, such as radio waves, microwaves, X rays and visible light.
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Section 12­3 notes.notebook
March 08, 2012
Pulse Wave ­ is a single, nonperiodic disturbance.
Periodic Wave ­ is a wave whose source is some form of periodic motion.
The sine graph is shown below and represents an example of periodic wave pattern. vibrating blade
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Section 12­3 notes.notebook
March 08, 2012
The wave below shows the wave traveling to the right. The vibrations of the rope will move perpendicular to the movement of the wave. Transverse Wave ­ is a wave whose particles vibrate perpendicularly to the direction of wave motion.
vibrating blade
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Section 12­3 notes.notebook
March 08, 2012
Crest ­ is the highest point above the equilibrium position.
Trough ­ is the lowest point below the equilibrium position.
Wavelength (λ)­ is the distance between two adjacent similar points of the wave, such as crest to crest or from trough to trough.
Crest
Trough
λ
amplitude
λ
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Section 12­3 notes.notebook
March 08, 2012
Longitudinal Wave ­ is a wave whose particles vibrate parallel to the direction of wave motion.
Examples of longitudinal waves are sound waves and a spring being stretched or compressed. The vibration caused by your hand on a rope or sound vibrations. When the vibrating particles of the medium complete one full cycle is one complete wavelength. The period of a wave is the amount of time required for one complete vibration of the particles of the medium. 5
Section 12­3 notes.notebook
March 08, 2012
Wave speed equals frequency times wavelength.
Speed of a Wave
v = f λ
speed of a wave = frequency x wavelength
A piano string tuned to middle C vibrates with a frequency of 264 Hz. Assuming the speed of sound in air is 343 m/s, find the wavelength of the sound waves produced by the string.
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Section 12­3 notes.notebook
March 08, 2012
Practice 12D ­ all
Section 12­3 Review ­ #1, 3, 4
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