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Types of waves & its difference

Aug 23, 2022
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Key Concepts

  • Waves
  • Types of Waves
  • Longitudinal Waves
  • Transverse Waves

Introduction:

When we drop a pebble in a pond, the disturbance created by the pebble generates water waves that travel away from the disturbance as shown in the figure.  

Waves on the surface of water-1 

If we observe the motion of a ball floating near the disturbance, we will see that the ball moves up and down and back and forth from its original position. However, the ball doesn’t undergo any net displacement from the motion of the waves. 

Conclusion: 

The motion of the ball indicates the motion of the particle in the water. The water molecules move locally, like the ball, but they don’t travel across the pond.  

The water wave moves from one place to another, but the water itself is not carried with it. 

Thus, in the above example: 

parallel

Waves -:  Spread out disturbances 

Medium-: Water in the pond 

Particles-: Water molecules 

Motion of water molecule on the surface of the water 

The water molecules move in vertical circles as waves pass. After the waves have passed the water returns to its original position.

Explanation:

  • A wave is a disturbance that carries energy through matter or space. 
  • Waves that transmit energy are of different types, some waves we can see some waves we cannot see. We can’t see electromagnetic waves and sound waves. 
  • Electromagnetic waves (light waves) are non-mechanical waves, they don’t require any medium to travel. They can even travel through a vacuum. 
  • Waves on the water surface, the waves that travel down a rope or a slinky, and sound waves are mechanical waves. Mechanical waves require a medium such as water, air, rope, or a slinky to travel.   

We can’t directly observe many waves like light waves and sound waves. The mechanical waves on a rope, waves on the surface of the water, and on a slinky are clearly visible to us. So, these mechanical waves can serve as a model to understand the wave phenomenon. 

parallel

Types of Waves: 

Types of waves

Transverse Waves: 

In the figure, we see a single disturbance is created on a rope. A single disturbance or a bump is called a wave pulse that travels through the medium.  

Transverse Waves on a string
 

Here we notice that the rope is disturbed in the vertical direction but the pulse travels horizontally. A wave with this type of motion is called a transverse wave. 

A transverse wave is one in which the vibrations are perpendicular to the direction of the wave’s motion. 

Example: Waves generated on a string. 

Transverse waves on a string

Longitudinal Waves: 

In the figure, we see a single disturbance is created on a slinky by squeezing together several turns and then suddenly released. A wave pulse of closely spaced turns will move away in both directions through the medium.  

Longitudinal waves on a slinky-1 

Here we notice that the slinky is disturbed in the same, or parallel to the direction of the waves’ motion. A wave with this type of motion is called a longitudinal wave. 

A longitudinal wave is one in which the vibrations are parallel to the direction of the wave’s motion. 

Example: Waves generated on a slinky. 

Longitudinal waves on a slinky-2 

Surface Waves: 

Waves that are deep in a lake or ocean are longitudinal; at the surface of the water, however, the particles move in a direction that is both parallel and perpendicular to the direction of wave motion, as shown in the figure.  

Surface waves 

This wave is a surface wave, which has characteristics of both transverse and longitudinal waves. 

Difference between Longitudinal and Transverse Waves: 

In a transverse wave when it propagates through a medium crests and troughs or hills and valleys are generated. 

Difference between longitudinal and transverse waves 

In a longitudinal wave when it propagates through a medium region of compressions and rarefactions are generated. 

Summary

  • A wave is a disturbance that carries energy through matter or space.
  • Electromagnetic waves (light waves) are non-mechanical waves, they don’t require any medium to travel. They can even travel through a vacuum.
  • Mechanical waves require a medium to travel. Waves on the water surface, the waves that travel down a rope or a slinky, and sound waves are mechanical waves.
  • In longitudinal waves, the medium particles vibrate parallel to the direction of propagation of the waves. In longitudinal waves, compressions, and rarefactions are generated.
  • In transverse waves, the medium particles vibrate perpendicular to the direction of propagation of the waves. In transverse waves Crests (hills) and Troughs (valleys) are generated.

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