Longitudinal Wave
A wave is a disturbance of a medium which transports energy through the medium without permanently transporting matter. In a wave, particles of the medium are temporarily displaced and then return to their original position. There are a variety of ways to categorize waves. One way to categorize waves is to say that there are longitudinal and transverse waves. In a transverse wave, particles of the medium are displaced in a direction perpendicular to the direction of energy transport. In a longitudinal wave, particles of the medium are displaced in a direction parallel to energy transport. The animation below depicts a longitudinal pulse in a medium.
The animation portrays a medium as a series of particles connected by springs. As one individual particle is disturbed, it transmits the disturbance to the next interconnected particle. This disturbance continues to be passed on to the next particle. The result is that energy is transported from one end of the medium to the other end of the medium without the actual transport of matter. In this type of wave - a longitudinal wave - the particles of the medium vibrate in a direction parallel to the direction of energy transport.
ngitudinal waves, one wave (1 λ) consists of a density and a tenuous.
In the picture above it appears that the direction of vibration parallel to the direction of wave propagation
In the picture above it appears that the direction of vibration parallel to the direction of wave propagation. A series of density and strain propagating along the spring. Density is the area where the coil spring toward each other, while the strain is the region where the coil spring away from each other. If you analyze the transversal wave has a pattern of peaks and valleys, the longitudinal wave consists of a pattern of density and strain. Wavelength is the distance between successive density or strain, respectively. What is meant here is the distance from the same two points and a sequence of density or strain (see the example in the picture above).
Distance traveled by a wave in one second is called propagation of waves. Fast wave propagation is denoted by v and its units m / s or m s-1. The relationship between v, f, λ, and T are as follows:
λ = v. T
λ = v / f
v = λ. f
Description:
λ = wavelength, unit meter ( m )
v = velocity of wave propagation, unit meters / second ( ms-1 )
T = wave period, the unit seconds or seconds ( s )
f = frequency wave, unit or 1/secs ( s-1
Waves are disturbances; they are changes in something - the surface of the ocean, the air, electromagnetic fields. Normally, these changes are travelling (except for Standing Waves); the disturbance is moving away from whatever created it.
For transverse waves the displacement of the medium is perpendicular to the direction of propagation of the wave. are easily visualized transverse waves
Most kinds of waves are transverse waves. In a transverse wave, as the wave is moving in one direction, it is creating a disturbance in a different direction. The most familiar example of this is waves on the surface of water. As the wave travels in one direction - say south - it is creating an up-and-down (not north-and-south) motion on the water's surface. This kind of wave is very easy to draw; a line going from left-to-right has up-and-down wiggles. So most diagrams of waves - even of sound waves - are pictures of transverse waves.
But sound waves are not transverse. Sound waves are longitudinal waves. If sound waves are moving south, the disturbance that they are creating is making the air molecules vibrate north-and-south (not east-and-west, or up-and-down. This is very difficult to show clearly in a diagram, so most diagrams, even diagrams of sound waves, show transverse waves.
Note:
It's particularly hard to show amplitude in longitudinal waves. Sound waves definitely have amplitude; the louder the sound, the greater the tendency of the air molecules to be in the "high" points of the waves, rather than in between the waves. But it's easier show exactly how intense or dense a particular wave is using transverse waves.
Speaking (or screaming!) compresses a region of air in the throat that subsequently travels through the atmosphere. Compress air and observe how the wave (displaced air) travels through the atmosphere, the decay of amplitude over time, the cause of an echo, and how a standing wave can be created.
Longitudinal waves may also be a little difficult to imagine, because there aren't any examples that we can see in everyday life. A mathematical description might be that in longitudinal waves, the waves (the disturbances) are along the same axis as the direction of motion of the wave; transverse waves are at right angles to the direction of motion of the wave. If this doesn't help, try imagining yourself as one of the particles that the wave is disturbing (a water drop on the surface of the ocean, or an air molecule). As it comes from behind you, a transverse waves lifts you up and then drops you down; a longitudinal wave coming from behind pushes you forward and then pulls you back. You can view animations of longitudinal and transverse waves here, single particles being disturbed by a transverse wave or by a longitudinal wave, and particles being disturbed by transverse and longitudinal waves. (There were also some nice animations of longitudinal waves available as of this writing at Musemath.)
Figure 1: In water waves and other transverse waves, the ups and downs are in a different direction from their forward movement. The highs and lows of sound waves and other longitudinal waves are arranged in the "forward" direction.Transverse and Longitudinal Waves
Transverse and Longitudinal Waves (wavetypes.png)
Longitudinal Waves
