Longitudinal Waves-Definition, Characteristics, And Examples

Longitudinal waves are types of waves in which the displacement of the medium is in the same direction as the traveling wave. Longitudinal waves are a type of mechanical wave that propagates energy and disturbances in the same direction as the wave travels.

What are longitudinal waves?

Longitudinal waves are waves in which the medium’s vibration is parallel to the direction of wave propagation and the medium’s displacement is in the same or opposite direction of wave propagation.

Mechanical longitudinal waves are also known as compressional or compression waves because they compress rarely as they move through a material, and pressure waves are because they generate pressure rises and reductions.

A wave down the length of a stretched Slinky toy, with the space between coils increasing and decreasing, is an effective depiction.

According to a study conducted by Dennison Bancroft, Longitudinal waves in cylindrical bars travel at a speed that depends on the bar’s diameter, Poisson’s ratio, and the wavelength of the wave. This speed can be calculated using a formula that takes into account these variables.

At very short wavelengths, the speed of the wave changes. The displacement of the wave also varies depending on the radius of the bar. A similar analysis can be applied to torsional and flexural waves^[1].

Explore this topic further in detail

How does Longitudinal Wave Propagate?

Can longitudinal waves be polarized?

How does the energy in a longitudinal wave move?

Why do longitudinal waves travel faster in solids?

Why is ultrasound a longitudinal wave?

Longitudinal waves Examples

Sound waves (pressure vibrations, displacement particles, and particle velocity conveyed in an elastic medium) and seismic P-waves are real-world examples.

Sound Waves

The amplitude of a sound wave is defined as the difference between the greatest pressure created by the wave and the pressure of undisturbed air. Sound propagation speed is affected by the type, content, and temperature of the medium through which it travels.

A sound wave is a type of longitudinal wave that is formed by the vibrating motion of particles traveling through a conductive medium. The tuning fork is an example of sound waves traveling in a longitudinal direction.

Pressure Waves

In seismology, a P wave or pressure wave is one of two forms of elastic body waves known as seismic waves. Because P waves move quicker than other seismic waves, they are the first to reach any afflicted area or seismograph following an earthquake. P waves may travel through gases, liquids, and solids.

Seismic Waves

Seismic waves are acoustic energy waves that flow through the Earth. It can be caused by an earthquake, volcanic eruption, magma movement, huge landslide, or major man-made explosion that generates low-frequency acoustic energy.

Seismologists study seismic waves by recording them with seismometers, hydrophones (in water), or accelerometers. Seismic waves differ from seismic noise (ambient vibration), which is continuous low-amplitude vibration caused by a number of natural and manmade causes.

Characteristics of Longitudinal Waves

These are some important characteristics of longitudinal waves.

Compression

Compression is a region in a longitudinal wave when the wave particles are closest to one other.

Rarefaction

Rarefaction occurs in a longitudinal wave when the particles are the furthest away from each other.

Wavelength

The wavelength of a longitudinal wave is the distance between two successive locations. These places might be located between two compressions or between two rarefactions.

Amplitude

The greatest displacement of a particle from its rest position is defined as its amplitude. The amplitude of a longitudinal wave is the distance from the medium’s equilibrium position to compression or rarefaction.

Period and Frequency

The period is the time it takes the wave to move one wavelength. The number of wavelengths per second is the frequency of the longitudinal wave.

Speed of Longitudinal wave

The speed of a longitudinal wave depends on the properties of the medium through which it is traveling. Specifically, it depends on the elasticity (or stiffness) and the density of the medium. The formula for the speed of a longitudinal wave in a medium is given:

v = √(E/ρ)

where v is the speed of the wave, E is the elasticity (or stiffness) of the medium, and ρ is the density of the medium.

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