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General Wave PropertiesLesson 1
Watch the Slinky…Slinky videos
http://www.youtube.com/watch?v=VnfiZfyQ2ywhttp://www.youtube.com/watch?v=upcTmdqrEe
o
What is a Wave?Transfer of energyIn the form of disturbance through some
medium*Without translocation of the medium
* Not all waves require a medium
Transverse Waveshttp://www.surendranath.org/Applets/Waves/
Twave01/Twave01Applet.html
Longitudinal Waveshttp://www.surendranath.org/Applets/Waves/
Lwave01/Lwave01Applet.html
Wave TerminologyDescriptions
Wave Terminology
Crest/Peak – high point of a transverse waveTrough – low point of a transverse wave
crest
trough
Wave Terminology
(In a longitudinal wave)Compression – region of high pressureRarefaction – region of low pressure
Wave Terminology
Phase – two points are said to be in phase if they are moving in the same direction and speed, with the same displacement from the rest position
p q p” q”p’ q’
Wave TerminologyWavefront – Imaginary line joining all points
in the same phase of vibration (e.g. all the crests)
Wave TerminologyQuantities
Wave Terminology
Amplitude – maximum displacement of a particle from its mean position (on either side)
SI Unit: m
A
A
AA
AA
Wave Terminology
Wavelength – distance between two successive particles which are oscillating in phase
SI Unit: m
Wave TerminologyFrequency (f): number of
vibrations/oscillations/cycles in 1 second.SI Unit: s-1 or Hz
Period (T): time taken for one complete vibration/oscillation/cycle.
SI Unit: s
T = 1/f
Wave EquationCalculating wave speed
Wave EquationWave speed/velocity (v): distance moved by
the wave in one secondSI Unit: ms-1
(Discuss) How to calculate v using the wave quantities covered earlier?
Wave EquationWith the wavelength and frequency of a wave, we know how many waves and how far the series of waves will cover per unit time. This is known as wave speed – distance traveled by a wave per unit time.
Recall speed =
So for waves, speed v = distance covered in 1 cycletime taken to cover 1 cycle
Recall f
so speed of waves v =
Speed equation for waves v = f (Unit : ms-1)
distance
time
wavelength
period
1
T
fT
1
T T
Test yourself…A fisherman notices that wave crests pass the bow of his anchored boat every 3.0s.He measures the distance between two successive crests to be 6.5m.How fast are the waves travelling?
EndComplete pages 1, 3, 7 of the Class Worksheet (Notes).