We are surrounded by waves. Waves are what allow us to see light, hear sound, and even feel the tides in the ocean or the vibrations in strings. Waves are vital to physics, particularly the two fundamental kind longitudinal and transverse waves.
Transverse and Longitudinal Waves
What is a Wave?
A wave is a disruption or vibration that moves energy from one place to another across a medium (such as air, water, or a solid) without causing the medium to move net.
A wave can be thought of as carrying energy rather than matter. For example, ripples are seen spreading outward when a stone is dropped into a calm pond. While the energy flows outward, the water merely oscillates up and down rather than moving.
Types of Mechanical Waves
For mechanical waves to move, a medium is required. These waves are separated according to the motion of the medium’s particles into:
Transverse Waves
Longitudinal Waves
1.Transverse Waves
Definition:
In transverse waves, the particles of the medium move perpendicular to the direction of wave propagation.
Example:
Imagine a rope on the ground. Waves will move along the rope if you grip one end and quickly jerk it up and down. However, rather than moving in the direction of the wave, the rope particles themselves move up and down. This wave is transverse.
Characteristics:
Crests and Troughs: A crest is the wave’s highest point, and a trough is its lowest.
The greatest deviation from the rest position is known as amplitude.
Wavelength (λ): The separation of two successive crests or troughs.
The number of waves that pass a location in a second is known as the frequency (f).
Speed (v): The wave’s rate of propagation across the medium.
Formula: v = f × λ
Where Do We See Transverse Waves?
Light waves (electromagnetic waves)
Water waves
Waves on a string
Note: Light waves are transverse but not mechanical they can travel through a vacuum.
2. Longitudinal Waves
Definition
The medium’s particles travel parallel to the wave’s path of propagation in longitudinal waves. An excellent example would be sound in the atmosphere. Our vocal cords vibrate and compress the air in front of them as we talk. As a result, the air undergoes a sequence of rarefactions and compressions.
Characteristics:
Compressions: Areas of intense pressure where particles are closely spaced.
• Rarefactions: Areas with low pressure where particles are dispersed.
• Amplitude: Associated with the variation in density between rarefactions and compressions.
• Wavelength: The separation of two rarefactions or compressions.
Speed: Also given by v = f × λ
Where Do We See Longitudinal Waves?
Sound waves in air or water
Vibrations in a spring or slinky
Seismic P-waves (primary waves during earthquakes)
Differences Between Transverse and Longitudinal Waves
Feature | Transverse Waves | Longitudinal Waves |
Particle Movement | Perpendicular to wave direction | Parallel to wave direction |
Medium | Solids, liquids, gases | Mostly solids and gases |
Example | Water waves, light waves | Sound waves, spring vibrations |
Wave Structure | Crests and troughs | Compressions and rarefactions |
The waves in an ocean are the combination of both longitudinal and transverse waves.
Generally, transverse and longitudinal waves travel with speed in same medium.
The particles motion in water waves involves a complicated motion.
Capillary waves are ripples of short wavelength and surface tension of water is responsible for restoring force.
Wavelength of gravity waves is of range from several meters to several hundred meters. The pull of gravity is responsible for restoring force in gravity waves.
Do All Waves Need a Medium?
Sound and other mechanical waves do require a medium. However, electromagnetic waves such as X-rays and light do not. Since they are not mechanical, they are able to travel through space. However, when examining transverse and longitudinal, we mostly concentrate on mechanical waves, such as sound and water waves.
Summary
We can have a better understanding of how energy flows around us by understanding longitudinal and transverse waves. Waves are always at work, whether it’s the sound of your favourite music, a pebble making ripples in water, or a stretched string vibrating in a guitar.
The medium’s particles flow perpendicular to the wave’s direction when it travels transversely. Particles in longitudinal waves travel parallel to the direction of the wave.
In general, transverse waves pass through solids and liquid surfaces with ease, but not through gases.
Sound in air is an example of a longitudinal wave that may pass through solids, liquids, and gases.
Since sound travels through a medium (such as air) as compressions and rarefactions, with particle motion parallel to the wave direction, it is a longitudinal wave.
Crest: A transverse wave’s highest point.
Trough: A transverse wave’s lowest point.
These stand for the greatest displacements, both positive and negative, from the rest position.
Compressions are regions of intense pressure where particles are densely packed.
Areas of low pressure where particles are dispersed are called rarifications.
A longitudinal wave is created by alternating these.