Date post: | 09-Jul-2015 |
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Representing Wave Features
If a series of waves were moving in water from left to right, the displacement of the medium (water) can be tracked using a cork. The cork could be seen to be going up and down.
Displacement-distance Graphs
An easy way to show the information in the previous diagram is by using a graph of particle displacement versus distance from the source.
The Speed of Waves
Calculate:1. The average speed of the
wave.2. The horizontal speed of
particle P3. The average vertical speed
of particle P between t = 0 secs and t = 0.025 secs
Solutions
Find the error!!!
Frequency of a Wave
All mechanical waves must have a vibrating source.
The frequency, f, of a source is the number of vibrations (cycles) that are produced each second. i.e. cycles per second.
1 cycle per second = 1 Hertz
Examples of Frequency
• What is the frequency of the second hand of a clock?
Frequency = 1cycle/60 sec Period = 60 sec
What is the frequency of US Presidential elections?
Frequency = 1 election/4 yrs Period = 4 yrs
Period of a WaveThe time interval for one cycle to be completed is called the Period, T,
and is measured in seconds.
The Period of a wave is best seen in a Displacement-Time Graph.
Frequency, f, and Period, T, show an inverse relationship and are connected by the formula:
Where f is the frequency of the wave in hertz (Hz)
T is the period of the wave in seconds (s).
Wavelength The Wavelength, λ, of a continuous wave is the distance
between two successive points of the same displacement and moving in the same direction.
Amplitude
The amplitude, A, of a wave is the maximum displacement of a particle from its mean (average) position.
THE WAVE EQUATION
The Wave Equation
TEXT: Page 239, Nos 6, 7, 9, 10.