l4 transverse waves revisited- reflection, interference, standing waves on string
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L4 Transverse Waves revisited- Reflection, Interference, Standing Waves on String. Transverse wave propagation. Wave reflection at a fixed end : the restoring force in the boundary material causes an upward pulse to become a downward pulse upon reflection. - PowerPoint PPT PresentationTRANSCRIPT
L4 Transverse Waves
revisited-Reflection, Interference,
Standing Waves on String
Transverse wave propagation
Wave reflection at a fixed end:the restoring force in the
boundary material causes an upward pulse to become a
downward pulse upon reflection
Wave reflection at an open end:the upward pulse maintains its
orientation upon reflection
PhET SimulationWave on a String
Wave Interference/Wave Superposition
Ct 4.5.2.sup
The pulse on the left is moving right, the pulse on the right is moving left. What do you see at the "central moment" they pass through one another?
Ct 4.5.2.sup
C
A
B
D
E
SIMwww.physics.nyu.edu/~ts2/Animation/waves.html
Suppose the pulse reflected from a boundary and moving to the left seen earlier meets another pulse
moving to the right…
Identical waves
movingin
oppositedirections
Motionof
pointalongthe
spring
Standing wave Applet
http://webphysics.davidson.edu/Applets/superposition/default.html
(Example 2)
Standing wave representation
Standing Wavesin a Stretched String
Conditions for standing waves
Recall thatf=v/λ
Hence fn =n f1
where f1 = v/(2L)
f1 is called the fundamental frequency (the lowest possible frequency)
All harmonics (n= 1,2,3,…) are possible excitations for a string held at both ends!
f2 is called the 2nd harmonic, and is also sometimes referred to as
the 1st overtone (especially in reference to sound).
f3 is the 3d harmonic or the 2nd overtone, etc.
Recall that v=f λ.Suppose we keep v and the length of the string constant.Can we establish a standing wave if we increase the vibrating frequency from f1 to 1.2 f1?A) yes B) noC) sometimes D) Not enough information given
Standing Waves on a String (rope)Demo