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Transverse and longitudinal waves review

Overview of key terms and skills for waves, including how to identify longitudinal and transverse waves.

Key terms

TermMeaning
WaveAn oscillation that transfers energy and momentum.
Mechanical waveA disturbance of matter that travels along a medium. Examples include waves on a string, sound, and water waves.
Wave speedSpeed at which the wave disturbance moves. Depends only on the properties of the medium. Also called the propagation speed.
Transverse waveOscillations where particles are displaced perpendicular to the wave direction.
Longitudinal waveOscillations where particles are displaced parallel to the wave direction.

How to identify types of waves

In a transverse wave, the particles are displaced perpendicular to the direction the wave travels. Examples of transverse waves include vibrations on a string and ripples on the surface of water. We can make a horizontal transverse wave by moving the slinky vertically up and down.
Figure 1: The parts of the slinky in a transverse wave move vertically up and down while the wave disturbance travels horizontally. Image credit: Adapted from OpenStax College Physics. Original image from OpenStax, CC BY 4.0
In a longitudinal wave the particles are displaced parallel to the direction the wave travels. An example of longitudinal waves is compressions moving along a slinky. We can make a horizontal longitudinal wave by pushing and pulling the slinky horizontally.
Figure 2: The parts of the slinky in a longitudinal wave and the wave disturbance travel horizontally. Image credit: Adapted from OpenStax College Physics. Original image from OpenStax, CC BY 4.0

Common mistakes and misconceptions

Sometimes people forget wave speed isn't the same as the speed of the particles in the medium. The wave speed is how quickly the disturbance travels through a medium. The particle speed is how quickly a particle moves about its equilibrium position.

Learn more

For deeper explanations of transverse and longitudinal waves, see our video introduction to waves.
To check your understanding and work toward mastering these concepts, check out the exercise on identifying transverse and longitudinal waves.

Want to join the conversation?

  • duskpin tree style avatar for user Phoebe Allanson
    Is there an easy way (an acrostic or something) to remember what wave is bunched together and which has up and down movement?
    (21 votes)
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    • starky ultimate style avatar for user mattijn.wow
      I find that the 'long' in longitudinal reminds me a bit of 'along'. As in along the medium. While the 'trans' out of transverse is more readily used in various fields and comes from Latin and translates to 'the other side of'. So it travels from one side to the other side. Hope it helps.
      (10 votes)
  • blobby green style avatar for user khushi singh
    here its written "Sometimes people forget wave speed isn't the same as the speed of the particles in the medium" but wont the increase in particle speed increase wave speed
    (16 votes)
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    • duskpin tree style avatar for user Natrium Chloride
      Nope, increasing particle speed does not increase the wave speed. They are separate. Actually it elaborated right after the sentence you quoted. 'The wave speed is how quickly the disturbance travels through a medium. The particle speed is how quickly a particle moves about its equilibrium position.' An increase in particle speed will increase the energy the wave carries but will not affect the wave speed at all.
      (9 votes)
  • starky sapling style avatar for user Areej Maqsood
    So if you move the slinky forwards and backwards, then the slinky with get bunched up in some places, like how the air was in the sound wave from the video, creating a longitudinal wave? But if you move it up and down, then the slinky with go up and down until you stop, like the string in the video, creating a transverse wave?
    (5 votes)
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  • blobby green style avatar for user Lora Beilharz
    So when a transverse and longitudinal wave combine, what is that called?
    (3 votes)
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    • blobby green style avatar for user tinagkp0551
      Longitudinal and transverse waves can combine to form what is known as a surface wave. One common example of this combination is the Rayleigh wave. In a Rayleigh wave, particles move in an elliptical or circular motion, combining both the back-and-forth (transverse) and compressional (longitudinal) motions. This kind of wave is frequently seen during seismic activity and plays a part in the surface of the earth trembling during an earthquake.
      (1 vote)
  • duskpin seed style avatar for user Kinzie
    If a wave length is so short, (gamma rays) can it be detected by machines? What are the effects of waves on a medium?
    (5 votes)
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  • duskpin tree style avatar for user cattuongvy1804
    Hi, I would like to ask about classifying waves. So waves are divided into 2 types: mechanical (e.g.: sound waves) and non-mechanical (e.g: light waves). Mechanical waves are further divided into transverse waves and longitudinal waves. Why are light waves longitudinal, yet they aren't considered mechanical? Thank you.
    (4 votes)
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  • hopper cool style avatar for user Captain Flash101
    what happens if both types of waves are mixed together.
    (3 votes)
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    • blobby green style avatar for user tinagkp0551
      Longitudinal and transverse waves can combine to form what is known as a surface wave. One common example of this combination is the Rayleigh wave. In a Rayleigh wave, particles move in an elliptical or circular motion, combining both the back-and-forth (transverse) and compressional (longitudinal) motions. This type of wave is often observed in seismic activity and contributes to the shaking of the earth's surface during an earthquake.
      (1 vote)
  • piceratops seed style avatar for user Jose Mari John Rebollos
    how does waves move through a medium?
    (1 vote)
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    • starky ultimate style avatar for user KLaudano
      If you are talking about physical waves, such as sound waves and vibrations, here is the answer. As the wave passes through a material, the particles at the wave are moving a very small distance. As they move, they bump into other particles and impart their momentum onto these new particles. These new particles in turn move and bump into other particles, repeating the cycle of movement and imparting momentum, thus allowing the wave to move through the medium.
      (4 votes)
  • sneak peak green style avatar for user Abacus
    "The particle speed is how quickly a particle moves about its equilibrium position." What does this sentence mean?
    (2 votes)
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    • blobby green style avatar for user tinagkp0551
      For example, if we watch a small slinky element performing a longidunal wave, we will see that element moving back and forth. We will also see that the element is moving with a restoring force throughout its motion, with the exception of one location—likely in the middle—that is referred to as the equilibrium position(no restoring force at this position), and the element's speed about that position is equal to the particle's or element's speed.
      (0 votes)
  • leafers seedling style avatar for user zachary chapman
    When I was reading I was a little cunfused about the
    (1 vote)
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