# longitudinal wave

## what is a longitudinal wave

A longitudinal wave is a type of mechanical wave. A mechanical wave is a wave that travels through matter, called the medium. In a longitudinal wave, particles of the medium vibrate in a direction that is parallel to the direction that the wave travels. You can see this in the Figure 1.1. The persons hand pushes and pulls on one end of the spring. The energy of this disturbance passes through the coils of the spring to the other end. Click image to the left or use the URL below. URL:

## compressions and rarefactions

Notice in the Figure 1.1 that the coils of the spring first crowd closer together and then spread farther apart as the wave passes through them. Places where particles of a medium crowd closer together are called compressions, and places where the particles spread farther apart are called rarefactions. The more energy the wave has, the closer together the particles are in compressions and the farther apart they are in rarefactions.

## p waves

Earthquakes cause longitudinal waves called P waves. The disturbance that causes an earthquake sends longitudinal waves through underground rocks in all directions away from the disturbance. P waves are modeled in the Figure Q: Where are the compressions and rarefactions of the medium in this model of P waves? A: The compressions are the places where the vertical lines are closest together. The rarefactions are the places where the vertical lines are farthest apart.

## instructional diagrams

No diagram descriptions associated with this lesson

## questions

a longitudinal wave is a type of mechanical wave.

``````-->  a. true

b. false
``````

in a longitudinal wave, particles of the medium vibrate in a direction that is perpendicular to the direction the wave travels.

``````a. true

-->  b. false
``````

earthquakes cause longitudinal waves called p waves.

``````-->  a. true

b. false
``````

a longitudinal wave that carries more energy has particles that are

``````a) closer together in rarefactions.

b) father apart in compressions.

c) the same distance apart everywhere.

-->  d) none of the above
``````

## diagram questions

No diagram questions associated with this lesson