- #1
jsmith613
- 614
- 0
I have a question about standing waves.
Is this what a standing wave is: a wave produced by a propagating wave and a reflected wave, resulting in a wave of zero propagation. A standing wave is produced, at a particular point, by the two propagating waves and it is simply a superposition of the two separate waves moving from out of phase to in phase stages (is this bit about phases correct)
see diagram: http://www.rmcybernetics.com/images/main/pyhsics/standing_wave.gif
The node is produced at a point with zero change in displacement / amplitude. It is a fixed point. This point remains fixed for two reasons
a) the superposition of the two points of the two waves ALWAYS equals zero
b) the waves cross at that point where the displacement of the point is zero.
An antinode are the moving peaks and or troughs of the wave. They form because
a) the superposition of the wave is either greater than or less than zero. BUT when the waves moving in opposing directions are in anti-phase, the two waves will cancel out producing an overall displacement of zero (antinodes can have a total displacmenent of zero but they can also reach maximum displacement as well)
is this all correct? is there anything else fundamental to the principal.
I presume standing waves DO exist in reality. The reason, when proven experimentally, that standing waves don't appear IMMEDIATLEY is due to the fact that it takes a little time for the waves to build up to maximum displacement and also we need to wait a little bit before the wave reflects. Correct?
A question on all of this: is it easy to identify from a still image at one point to identify where the nodes would be. Also what has this got to do with harmonics? (Fundemental harmonic, second harmonic (first overtone) ...)
Thanks
Is this what a standing wave is: a wave produced by a propagating wave and a reflected wave, resulting in a wave of zero propagation. A standing wave is produced, at a particular point, by the two propagating waves and it is simply a superposition of the two separate waves moving from out of phase to in phase stages (is this bit about phases correct)
see diagram: http://www.rmcybernetics.com/images/main/pyhsics/standing_wave.gif
The node is produced at a point with zero change in displacement / amplitude. It is a fixed point. This point remains fixed for two reasons
a) the superposition of the two points of the two waves ALWAYS equals zero
b) the waves cross at that point where the displacement of the point is zero.
An antinode are the moving peaks and or troughs of the wave. They form because
a) the superposition of the wave is either greater than or less than zero. BUT when the waves moving in opposing directions are in anti-phase, the two waves will cancel out producing an overall displacement of zero (antinodes can have a total displacmenent of zero but they can also reach maximum displacement as well)
is this all correct? is there anything else fundamental to the principal.
I presume standing waves DO exist in reality. The reason, when proven experimentally, that standing waves don't appear IMMEDIATLEY is due to the fact that it takes a little time for the waves to build up to maximum displacement and also we need to wait a little bit before the wave reflects. Correct?
A question on all of this: is it easy to identify from a still image at one point to identify where the nodes would be. Also what has this got to do with harmonics? (Fundemental harmonic, second harmonic (first overtone) ...)
Thanks