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Title: What's the difference between wave propagation velocity and particle oscillation velocity? Post by: illkidxy4 on Dec 17, 2012 So far, I have that a wave propagation velocity is the speed at which a wave front passes through a medium relative to the speed of light.
I have read that particle oscillation velocity can either be parallel or perpendicular in regards to a longitudinal and transverse wave. But what is the difference? The wave propagation velocity is paralell to the particle oscillation velocity such that they move relative to each other - but the wave is the larger motion that portrays the sum of the particle motion? Title: What's the difference between wave propagation velocity and particle oscillation velocity? Post by: Leobgood on Dec 17, 2012 It might be easier to start with the difference in the context of a surface gravity wave in water.
When a water wave passes a point, to first order, the water particles move in closed vertical circular paths whose radius decreases linearly with depth (circles get smaller as you increase depth.) The water wave moves at a constant velocity perpendicular to the depth whereas the water particles merely oscillates in place. So while the two speeds are related, the two speeds are generally different. The same concept applies to electromagnetic waves that encounter a medium. They cause charged particles to oscillate with zero net displacement as the wave passes. |