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Sound

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Overview

Sound is the form of energy, which is produced by vibration of molecules of a body. Sound travels in the form of a wave. Mechanical waves can be propagated only in material medium whereas electromagnetic waves do not require any material medium for propagation. This note provides us the information about sound and its propagation as wave.
Sound

The sound is the form of energy, which is produced by vibration of molecules of a body. Sound travels in the form of a wave. Like light, it also undergoes reflection, refraction etc.

Wave

The path of energy, through which the energy travels is called a wave. The wave can also be defined as the periodic disturbance of the particles of the medium. The waves can be classified into two types’ mechanical waves and electromagnetic wave. Mechanical waves can be propagated only in material medium whereas electromagnetic waves do not require any material medium for propagation.

Wave in water surface

when a stone is dropped into a pool of water, circular waves spread out on all directions on the surface from the center of disturbance. There are circular regions called crest, where the water level is above the normal level and there are other circular regions, called trough, where the water level is below the normal level. Water waves on the surface of water are the examples of wave motion.

Waves in rope:

If a rope held horizontally, is fixed at one end and the free end is moved up and down at right angle, a disturbance consisting of a series of crests and troughs travel along the rope.

Sound wave:

A wave of compression and rarefaction, by which sound is propagated in an elastic medium such as air is known as sound wave.

Disturbance set up in a medium is called a wave and the propagation of disturbance, without involving transfer of any material within it, is called wave motion.

Types of wave motion

Waves can be classified into two types on the basis of the nature of the vibration in particles of the medium. They are transverse wave and longitudinal wave.

Comparison of transverse and longitudinal wave

Transverse waves

Longitudinal waves
Vibrations of particles of a medium are perpendicular to the direction of propagation of wave. Vibrations of particles of a medium are along the direction of propagation of wave.
These waves can be generated in solids and liquids. These waves can be generated in solids, liquids and gases.
A complete wave consists of a crest and trough A complete wave consists of a compression and rarefaction.
It can travel in vacuum. It cannot travel in vacuum.
Speed of this wave is more. Speed of this wave is less.

image source:http://lh3.ggpht.com/-tX6BKR8nUBI/Uf8fnKlf8OI/AAAAAAAAHSE/L8k31m6xw5o/Difference between Longitudinal wave and Transverse wave_thumb[13].jpg?imgmax=800

Things to remember
  • Sound is the form of energy, which is produced by vibration of molecules of a body. Sound travels in the form of a wave.
  • The path of energy, through which the energy travels is called wave.
  • Mechanical waves can be propagated only in material medium whereas electromagnetic waves do not require any material medium for propagation.
  • Disturbance set up in a medium is called a wave and the propagation of disturbance, without involving transfer of any material within it, is called wave motion.
  • It includes every relationship which established among the people.
  • There can be more than one community in a society. Community smaller than society.
  • It is a network of social relationships which cannot see or touched.
  • common interests and common objectives are not necessary for society.
Videos for Sound
Sound, Vibration, Wave Characteristics
Transmission of Sound - Designmate
Transverse and Longitudinal Waves
Transverse and Longitudinal Waves
Questions and Answers
A sensation caused in the ear by the vibration of the air and any other medium is called sound.
The sound is produced due to the vibration of the molecular medium (i.e. objects).
Any vibrating objects can produce sound. So, the vibrating objects are called sources of sound. For example, vibration of string in guitar, air in flute, etc.
Wave is a propagation of disturbance that carries energy from a vibrating object without transfer of any material within it. Eg: sound wave, light wave, etc.
The waves which need material medium for their propagation are called mechanical waves.

The sound wave carries energy from a vibrating object as kinetic energy of the particles of material medium (solid, liquid or gas), so sound waves are called mechanical waves.

Sound waves are mechanical waves that need material medium to carry energy from the sources. So, they cannot travel in vacuum.

The differences between transverse and longitudinal wave are as follows:
Transverse wave Longitudinal wave
  1. It is the wave in which the particles of the medium vibrate perpendicular to the direction of the propagation of the wave. Eg: wave produced in rope and ponds.
  1. It is the wave in which the particle of the medium vibrates along the direction of the propagation of light. Eg: sound waves.
  1. These waves can be generated in solids and liquids.
  1. These waves can be generated in solid, liquid and gas.

Sound cannot travel in vacuum because sound is a mechanical wave that needs material medium to transfer energy.

The propagation of disturbance, without involving transfer of any material within it, is called wave motion. There are two types of wave motion. They are transverse and longitudional wave.
When the displacement of a particle is maximum above its mean position is called Crest. When the displacement of a particle is maximum below its mean position is called Trough
Sound is the form of energy which is produced by vibration of molecules of a body.
The number of complete oscilations made by the oscilating body in one second is called its frequency.
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