Speed of particles of a wave vs the wave speed

In summary, the speed of oscillations of a particle in a wave is not equal to the wave traveling velocity. The speed of a wave and the speed of particles can have different values. When light passes through a medium, the amount of light that goes through and the amount that is reflected depends on the medium. Additionally, when light in one medium hits a surface of another medium, there is always some reflection. The particles being referred to in this conversation are the particles of the medium through which the mechanical wave travels. The speed of sound in gases is mainly determined by temperature.
  • #1
huey910
36
0
I have always thought that the speed of oscillations of a particle in a wave = wave traveling velocity - is that not correct? In addition, when light passes through a medium, does only part of it go through and the rest reflected? Or does that only happen when it is going from a denser medium to a less dense one? Thank you.
 
Physics news on Phys.org
  • #2
huey910 said:
I have always thought that the speed of oscillations of a particle in a wave = wave traveling velocity - is that not correct?

yes that is not correct. Speed of wave is the speed of disturbance in the medium.
 
  • #3
Which 'particles' do you refer to?
 
  • #4
huey910 said:
In addition, when light passes through a medium, does only part of it go through and the rest reflected?
That depends on the medium, and your question is too general for a general answer.
If light in one medium hits a surface of another medium, usually a part of the light gets reflected.

The speed of a wave and the speed of particles can have different values.
 
  • #5
When the speed changes at a single interface, there is always some reflection. This reflection can be eliminated at some wavelengths by 'blooming' (optical) or 'matching' (at RF) but it's there because of boundary conditions.

And I still don't know what 'particles' are being referred to.
 
  • #6
the particles I have in mind are the particles of the medium through which the mechanical wave travels
 
  • #7
The air molecules have a wide distribution of velocities (from zero the many times the speed of sound). The speed at which sound travels is linked pretty much to the mean speed of the particles. That is the main cause for the delay in propagation of the pressure waves as that determines the time taken for one (average) molecule to bump into the next one. Hence, it is mainly Temperature that determines the speed of sound in gases. (It is independent of pressure over a huge range of pressures).
 

FAQ: Speed of particles of a wave vs the wave speed

1. What is the difference between the speed of particles in a wave and the wave speed?

The speed of particles in a wave refers to the individual motion of the particles within the wave. This can vary depending on the medium the wave is traveling through. On the other hand, the wave speed refers to the speed at which the wave as a whole travels through the medium. This is determined by the properties of the medium, such as density and elasticity.

2. Is the speed of particles always the same as the wave speed?

No, the speed of particles and wave speed can be different. In some cases, the particles may move faster or slower than the wave itself. For example, in a water wave, the particles move in a circular motion while the wave itself moves forward.

3. Why does the wave speed remain constant while the speed of particles can change?

The wave speed is determined by the properties of the medium, which remain constant as long as the conditions of the medium do not change. However, the speed of particles can change if the medium changes, such as temperature or pressure changes. This is because the individual particles are affected by these changes in the medium.

4. How does the speed of particles affect the overall speed of a wave?

The speed of particles can affect the overall speed of a wave in some cases. For example, if the particles in a medium are moving faster than the wave speed, they can create a shock wave, which travels faster than the wave itself. In other cases, the speed of particles may not have a significant impact on the wave speed.

5. Can the speed of particles and the wave speed be measured differently?

Yes, the speed of particles and the wave speed can be measured differently. The speed of particles can be measured using methods such as Doppler radar, while the wave speed can be measured using techniques like time-of-flight measurements or frequency analysis. Both measurements can provide valuable information about the behavior of waves and particles.

Back
Top