Have you ever noticed a slinky or a spring waving back and forth, just like shown below? This type of motion in which particles move along the direction of the wave back and forth is a longitudinal motion.
Longitudinal waves are the waves in which the particles of the medium propagates along the direction of the motion. Simply, particles travel along the direction of the motion or a wave. They are composed of compression (when particles/wave move close to each other) and rarefaction (when particles/wave move away). They require a medium to travel.
Let’s explore the examples of Longitudinal wave in our daily life.
1. Speaking on the mic
A sound wave is a significant example of a longitudinal wave. When a speaker speaks some words in front of the microphone, he/she hit the air thousands of time per second at different frequencies. The sound particles travel along with the air particles and enter the mic to produce sound.
When we clap while singing a birthday song or on any other occasion, do you know, what makes our hand produce that familiar sound of a clap. When we applaud, we compress and displace the air particles between our hands for a part of a second, which produces the sound of a clap we are familiar with.
3. Vibrating Drumheads
All of us are familiar with the sound of a drum, and most of us have also tried hitting the drum in different beats. When we hit the drum with the mallet, drum head vibrates and produce soundwaves. The soundwaves are generated because the drum head moves outward and inward, making air particles to move (vibrate) in the same direction.
4. Tsunami Waves
Tsunamis cause damage to coastal regions and that’s why people residing in coastal areas are afraid of them. Most people think that sea waves are a transverse wave as they go up and down. However, sea waves, including Tsunami, are the example of both transverse as well as a longitudinal wave. When the waves reach the shore or smaller areas, they become smaller and thinner, and water particles move parallel to the wave, hence making it a longitudinal wave.
5. Earthquake (Seismic-P wave)
It is said that animals can sense the earthquake waves much before humans. They have the ability to sense the seismic P waves, which travel only in the interior of the earth. Even humans can feel a little bump and rattle of these waves, but they are mostly unnoticeable to us. The P waves are the fastest, and they require a medium to travel (solid and liquid). These waves cause the interior of the earth (tectonic plates) to move back and forth in a longitudinal manner, which leads to the surface waves (seismic S wave), which we can feel.
6. Vibration in Window Panels after a Thunder
Whenever it is raining heavily, and thunders are there, you might have noticed the vibration in window panels of your home; it happens because of sound waves. Lightning causes an increase in the air pressure and temperature, which creates a shock wave of sound that we hear like a loud boom and cause our window panels to vibrate.
7. Music Woofers
Have you ever noticed the movement of the woofer cone; moving in and out or ever felt air pressure on your hand when you try to cover the mouth of a woofer? It’s because woofers work on the phenomenon of a longitudinal wave. They move the air particles in or out, producing sound.