Let’s Get Physics-l: Wave Motion

We come into contact with waves on a daily basis. Sound waves allow us to hear the world around us (Even annoying siblings who won’t stop singing…). We use microwaves to rapidly vibrate water molecules, generate heat which we use to cook food quickly. Radio waves and Infrared allow us communicate with people across the globe as well as watch great TV shows. As is probably apparent, waves are a pretty handy thing in our universe with a wealth of useful functions that Humanity have managed to implement in everyday life.

Progressive waves are the type of wave we use the most. They are waves that can transfer energy from one location to another. Progressive waves can be broken down into two sub groups: Transverse and Longitudinal. Longitudinal waves cover sound waves and certain types of seismic waves known as P waves. Transverse waves include the electromagnetic waves, such as gamma rays and visible light.

Longitudinal waves are more restricted in terms of where they can go. Longitudinal waves transfer energy through a medium, a medium being a solid, liquid or gas, via vibrations (Much like Mechanical waves that also transfer energy through a medium). These vibrations travel parallel to the direction of energy transfer. The best superhero examples I can think of accommodate Marvel and DC fans alike. Consider the power sets of Quake or Black Canary (Marvel and DC respectively for those who aren’t aware).


Longitudinal waves. The thicker lines are the compressions. The thinner lines are the rarefactions.



Quake is able to generate seismic waves with her hands which can be seen rather well on the Agents of Shield TV show. When she releases these seismic waves, they form a pattern similar to those seen in longitudinal waves: Areas of compression (Close together) and Areas of rarefaction (Spaced out).



The rings represent areas of compression and the space between rarefaction (Note: the size difference is not accurate, that’s just how they look on Agents of Shield).


Black Canary is able to emit her ultrasonic Canary Cry to deal damage to both organic and inorganic items. As seen below, this cry looks similar to a longitudinal wave, compressions and rarefactions in a pattern.

Image result for DC Canary cry
Again, the rings represent the compressions and the space between them is the rarefaction.

Transverse waves are effectively limitless in what they can travel through. They can pass through the vacuum of space, hence limitless travel, and they transfer energy perpendicular to the direction of energy transfer. The particles in transverse wave only move up and down, not forwards and backwards.


A Transverse Wave



  • Progressive Waves – Waves that transfer energy from one place to another.
  • Longitudinal Waves – Parallel to direction of energy transfer. They include sound waves and some seismic waves.
  • Transverse Waves – Perpendicular to direction of energy transfer. They include the electromagnetic waves.

There you have it, an introduction to waves and their motion. We will take a closer look at the terminology we use when describing waves in the next waves related post. Please leave any thoughts or questions in the comments and I’ll be happy to help where I can. Thank you.

(The characters referenced are property of Marvel and DC comics and I in no way lay claim to them. Nor do I lay claim to the image of Black Canary, that is property of DC Comics and the Artist who drew it. They have simply been used to help demonstrate ideas).



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