Need Help?

Get in touch with us

bannerAd

Sound and its Properties- Sound Waves

Aug 19, 2022
link

Sound And Its Properties

 Key Concepts

  • Vibrations and formation of sound
  • Types of sounds
  • Propagation of sound

Sound wave: 

Sound has two types of waves  

  1. Longitudinal wave 
  1. Transverse wave 

Longitudinal wave: 

The particles in the wave oscillate parallel to the way of propagation of the wave; such type of wave is called a longitudinal wave.  

In longitudinal waves, there are alternate compression and rarefactions.  

Transverse wave:  

The particles in the wave oscillate perpendicular to the way of propagation of the wave; such type of wave is called a transverse wave.  

In transverse waves, there are alternate crests and troughs.   

parallel

Amplitude: 

The maximum displacement or displacement of the wave from the mean position or equilibrium position is called amplitude transverse waves. 

Wavelength: 

The wavelength is between two consecutive crests, troughs, or two consecutive compressions or rarefaction. 

Wavelength is denoted by λ(lambda), and units of the wavelength are m(meters) in the SI system. 

Frequency: 

The number of cycles per second is called frequency; the number of waves passing through the specific point is called a cycle.  

Frequency is denoted by υ(nu), and units of the frequency are hertz. 

parallel

Wave speed: 

The distance travelled by the wave in the given amount of time is called wave speed.  

Speed of wave = wavelength x frequency 

Wave speed is denoted by meter Hertz (MHz). 

biosphereExplanation

Formation of sound: 

Every vibrating body produces sound.  

Let’s consider a steel plate in the kitchen. If the plate is vibrated, then there is the production of sound which means that the vibrating body produces sound, and also after some time, the plate stops vibrating, and the sound will be disappeared. Those types of vibrations are called damped vibrations, which travel with decreasing amplitude are called damped vibrations. 

Important points of formation of sound: 

  1. Every vibrating produces sound. 
  1. If a body is at rest and not vibrating, then the body doesn’t produce sound. 
  1. Vibration with decreasing amplitude is called damped vibration.  

Types of sounds: 

Depending upon the measurement of sound, sound has three types: 

  1. Infrasound 
  1. Normal sound 
  1. Ultrasound 

Measurement of sound: 

The intensity of sound is measured in decibels. A human ear can hear sounds between 20 Hz to 20000 Hz.  

Infra-sound: 

Sounds that are less than 20 Hz are called infrasound. The human ear cannot hear infrasound which has very little frequency.  

Audible sound:  

Audible sounds are from 20 Hz to 20000 Hz. The human ear can hear normal sounds.  

Ultrasound: 

Sounds that are more than 20000 Hz are called ultrasound. The human ear cannot hear ultrasound which has more frequency.  

Propagation of sounds: 

Sounds can propagate from one point to another in a medium. 

Propagation of sounds in  

  1. Solids 
  1. Liquids  
  1. Gases  

Propagation of sound in solids: 

Particles in the solids are closely packed. If the particles are disturbed, then the disturbance will propagate very fast, as the particles are closely packed. 

Hence, the speed of sound in solids is very high. The speed of sound in iron is 3960 m/s.  

Propagation of sound in liquids: 

Particles in the liquids are moderately packed. If the particles are disturbed, then the disturbance will propagate at a medium pace, as the particles are moderately packed.  

Hence, the speed of sound in liquids is moderate. The speed of sound in liquids is 1230 m/s.  

Propagation of sound in gases: 

Particles in the gases are loosely packed. If the particles are disturbed, then the disturbance will propagate at a slow pace, as the particles are loosely packed, Hence the speed of sound in gases are slow, speed of sound in gases is 330 m/s. 

Summary

Formation of sound:

  1. Every vibrating produces sound.
  2. If a body is at rest and not vibrating, then the body doesn’t produce sound.
  3. Vibration with decreasing amplitude is called damped vibration.

Measurement of sound:

The intensity of sound is measured in decibels. A human ear can hear sounds between 20 Hz to 20000 Hz.

Infrasound:

Sounds that are less than 20 Hz are called infrasound. The human ear cannot hear infrasound which has very little frequency.

Normal sound:

Normal sounds are from 20 Hz to 20000 Hz. The human ear can hear normal sounds.

Ultrasound:

Sounds that are more than 20000 Hz are called ultrasound. The human ear cannot hear ultrasound which has more frequency.

Propagation of sound in solids:

Particles in the solids are closely packed. If the particles are disturbed, then the disturbance will propagate very fast, as the particles are closely packed.

Propagation of sound in liquids:

Particles in the liquids are moderately packed. If the particles are disturbed, then the disturbance will propagate at a medium pace, as the particles are moderately packed.

Propagation of sound in gases:

Particles in the gases are loosely packed. If the particles are disturbed, then the disturbance will propagate at a slow pace, as the particles are loosely packed.

Comments:

Related topics

Define Position Time Graph and its Types

Key Concepts • Slope of a graph • Position time graph • Slope of s-t graph = Velocity • Types of position time graphs Introduction An object in a uniform motion covers equal distances in equal intervals of time. This also indicates that it moves at a constant velocity. When its position at different instants […]

Read More >>

Magnetic Field Lines: Definition, Explanation and Q&A

Key Concepts Magnetic Field Magnetic Field Lines properties of magnetic field lines Uniform and non uniform magnetic lines Introduction Two magnets when placed close to each other attract and stick to each other. However, if we go on increasing the distance between them, the attraction between them reduces gradually to such an extent that they […]

Read More >>

The Life Cycles of Stars: Meaning and Example

Key Concepts Stars Analysis of starlight Composition of stars Stars’ temperature Size and mass of stars Stages of life cycle of a star Introduction Stars are huge, shining balls of extremely hot gas (known as plasma) in space. The Sun is our nearest star. During the nighttime, many other stars are visible to the naked […]

Read More >>

Mirror Formula

Key Concepts New cartesian sign convention Mirror formula Solving problems using the mirror formula Introduction When dealing with the reflection of light by spherical mirrors mathematically, a set of sign conventions is followed, called the New Cartesian Sign Convention. According to this convention, the pole of a spherical mirror is taken as the origin and […]

Read More >>

Other topics