Waves and it types
Neha Kishor
A wave is called propagating dynamic disturbance of one or more quantities. Waves can be periodic, in such a way that, the quantities oscillate repeatedly about an equilibrium value at any frequency. A wave is said to be a travelling wave, when the entire waveform moves in one direction, Infract a pair of superimposed periodic waves travelling in opposite directions form a standing wave.
In the case of a standing wave, the amplitude of vibration has nulls at some positions. At that point, the wave amplitude appears to be smaller or even zero. Waves can be described by a wave equation. A standing wave field of two opposite waves. Or one-way wave equation for single wave propagation in a direction that is defined.
Two types of waves are most commonly known to us
1)Mechanical wave
2)Electromagnetic waves (EM waves)
In a mechanical wave, strain and stress fields oscillate about a mechanical equilibrium. A mechanical wave is a local deformation (strain) in some physical medium that propagates from particle to particle that creating local stress. That causes strain in neighbouring particles too. Consider an example, sound waves are variations of the local pressure and particle motion that propagate through the medium. Some more examples of mechanical waves are seismic waves, surface waves, gravity waves, string vibrations and vortices.
But in the case of an electromagnetic wave such as light, coupling between the electric and magnetic fields sustains the propagation of a wave. These fields are based on Maxwell’s equations. EM waves can travel through a vacuum. Also, it can able to travel through some dielectric media at a wavelength where that is considered transparent. According to their frequencies, Electromagnetic waves, (or wavelengths) have more specific classifications including radio waves, terahertz waves, ultraviolet radiation, infrared radiation, visible light, X-rays and gamma rays.
Other types of waves include gravitational waves .This wave is formed by the disturbances in spacetime which propagate according to general relativity,
Heat diffusion waves;- plasma waves that combine mechanical deformations and electromagnetic fields.
Reaction–diffusion waves, such as in the Belousova–Zhabotinsky reaction; and many more.
Mechanical and electromagnetic waves transfer information, momentum, and . But they do not transfer particles in the medium. Some waves have envelopes which do not move at all .They are standing waves ,which are fundamental to music and hydraulic jumps. Some, like the probability waves of quantum mechanics, may be completely static.
A physical wave field is always confined to finite region of space, known as its domain. For instance, the seismic waves generated by earthquakes are significant only in the interior and surface of the earth. So, it is ignored outside the earth. But the waves that has infinite domain, that extend over the whole space, are very important tool for understanding physical waves in finite domains.
A plane wave has the disturbance which is identical along any plane and normal to a specific direction of travel. In general , the simplest wave is a sinusoidal plane- wave in which ,the field experiences simple harmonic motion at one frequency. Complicated waves can generally considered as the sum of many sinusoidal plane waves ,having different directions of propagation and/or different frequencies.
A plane wave is classified as a transverse wave when the field disturbance at each point is described by a vector which is perpendicular to the direction of propagation.
A wave is called longitudinal wave if those vectors are aligned with the direction of propagation. In case of mechanical waves, both transverse and longitudinal waves are included; on the other hand, electromagnetic plane waves are rigorously transverse. While the sound waves in fluids can only be longitudinal.
Types of Waves.
Waves are classified on the basis of the direction of movement of the individual particles in the medium relative to the direction in which the waves travel. They are
- Transverse waves
- Longitudinal waves
- Surface waves.
A transverse:-
Wave in which particles of the medium move in a direction perpendicular to the direction that the wave moves. For example a slinky is stretched out in a horizontal direction and there a is pulse is introduced into the slinky on the left end by vibrating the first coil up and down. Energy is transported through the slinky from left to right. As the energy is transported from left to right, the individual coils of the medium are displaced upwards and downwards. In this case, the particles of the medium move perpendicular to the direction that the pulse moves. This type of wave is a transverse wave.
A longitudinal wave
A wave in which particles of the medium move in a direction parallel to the direction in which the wave moves. Eg: a slinky is stretched out in a horizontal direction and that a pulse is generated into the slinky on the left end by vibrating the first coil left and right. Energy is transported through the slinky from left to right. As the energy is transported from left to right, the individual coils of the medium will be displaced leftwards and rightwards. In this case, the particles of the medium move parallel to the direction that the pulse moves. This type of wave is a longitudinal wave.
A surface wave
It is a type of wave in which particles of the medium undergo a circular motion. Surface waves are neither transverse nor longitudinal. In longitudinal and transverse waves, all the particles in the medium move in a parallel and a perpendicular direction according to the direction of energy transport. In a surface wave, it is only the particles at the surface of the medium that undergo the circular motion. The motion of particles tends to decrease as one proceeds further from the surface.
Read More : Möbius strip
Check your knowledge
Waves are most commonly caused by wind. Wind-driven waves, or surface waves, are created by the friction between wind and surface water. As wind blows across the surface of the ocean or a lake, the continual disturbance creates a wave crest.
To summarize, waves carry energy. The amount of energy they carry is related to their frequency and their amplitude. The higher the frequency, the more energy, and the higher the amplitude, the more energy.
Sound waves fall into three categories: longitudinal waves, mechanical waves, and pressure waves
Transverse waves cause the medium to move perpendicular to the direction of the wave. Longitudinal waves cause the medium to move parallel to the direction of the wave.
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