What is Waves & Types of Waves

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What is Waves & Types of Waves

What is Waves & Types of Waves

Waves

A wave is a disturbance which propagates energy from one place to the other without the transport of matter.

These are of two types
1. Mechanical waves
2. Electromagnetic waves

1. Mechanical Waves

The waves which require material medium (solid, liquid or gas) for their propagation are called mechanical waves or elastic waves.

These are of two types

1. Longitudinal waves
2. Transverse waves

2. Electromagnetic Waves

  • The wave which do not require medium for their propagation i.e., which can propagate even though the vacuum are called electromagnetic wave. They propagate as transverse wave.
  • The wavelength range of electromagnetic wave is 10m to 104 m.
  • Cathode rays, canal rays, O-rays, B-rays are not electromagnetic waves. Light and heat are examples of electromagnetic waves.

Sound Waves

  • It is longitudinal mechanical waves.
  • The longitudinal mechanical waves which lie in the range 20 Hz to 20000 Hz are called audible or sound waves.
  • These are sensitive to human ear.
  • The longitudinal mechanical waves having frequencies less than 20 Hz are called infrasonic. These are by earthquakes, volcanic, eruption, ocean waves and elephants and whales.
  • The longitudinal mechanical waves having frequencies greater than 20000 Hz are called ultrasonic waves.
  • Ultrasonic waves are used for sending signals, measuring the depth of sea, cleaning clothes and machinery parts of clocks, removing lamp shoot from chimney of factories and in ultrasonography.

Speed of Sound

  • Speed of sound is maximum in solids and minimum in gases.
  • Speed of sound in air is 332 m/s, in water is 1483 m/s
  • Speed of sound basically depends upon elasticity and density of medium.
  • Speed of sound remains unchanged by the increase or
  • The speed of sound increases with the increases of temperature of the medium. The speed of sound in air decrease of pressure.
  • increases by 0.61 m/s when the temperature is
  • increased by 1°C.
  • The speed of sound is more in humid air than in dry air
  • because the density of humid air is less than the density of dry air.

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