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Wave Characteristics - St. Mary's Physics Online II. Characteristics of Periodic Waves A. Frequency (f) = # vibrations/sec = # of cycles/sec = Hertz (Hz) Frequency - St. Mary's Physics Online
- determined by source of wave
cycle = (one single vibration)
How many cycles between the dots?
3 Cycles
Ex) 10 cycles pass a fixed point in a wave train in 5 seconds. What is the frequency of the wave?
Top view - St. Mary's Physics Online
Top view of a periodic wave
Crest - Physics 2000
Top view of a periodic wave
A wave generator operating for 4 seconds produces the waves drawn above.
What is the frequency of this periodic wave train?
How many waves are drawn between A and B? (Be careful!!)
8 cycles
f = 8 cycles/4 sec
Human ear: Frequency range - 20 Hz - 20,000 Hz. Ringtones the old folks can't hear
Ear Animation - 2006 McGraw-Hill Higher Education
B. Period – time for an entire wave cycle to pass a given point in a medium - determined by source of vibration not medium
The frequency of a light wave is 5.0 x 1014 hertz. What is the period of the wave? a) 2.0 x 10-15 s b) 6.0 x 10-7 s
c) 1.7 x 106 s d) 5.0
x 10-14 s
T = 1/f = 1/(5.0 x 1014 hertz)
a) 2.0 x 10-15 s
Jan 2004 Which has the largest period?
B
C. Amplitude – maximum change in position of a particle from its rest position during a single vibration Amplitude - St. Mary's Physics Online - determined by source of vibration not medium 2 waves A & B
same frequency
1. Amplitude of a wave shows the amount of energy in the wave
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