Physics
Wave Characteristics
Wave characteristics refer to the properties and behaviors of waves, including amplitude, frequency, wavelength, and speed. Amplitude is the maximum displacement of a wave from its rest position, while frequency is the number of wave cycles per unit of time. Wavelength is the distance between two consecutive points on a wave, and speed is the rate at which a wave travels through a medium.
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5 Key excerpts on "Wave Characteristics"
eBook - PDFWaves and Oscillations in Nature
An Introduction
- A Satya Narayanan, Swapan K Saha(Authors)
- 2015(Publication Date)
- CRC Press(Publisher)
The incident idealized photon is monochromatic in nature. The corresponding classical wave has the same extent as well. For a wave traveling through a medium, a crest is seen moving along from particle to particle. This crest is followed by a trough which, in turn, is followed by the next crest. A distinct wave pattern in the form of a sine wave is observed traveling through the medium. This sine wave pattern continues to move in uninterrupted fashion until it encounters another wave along the medium or until it encounters a boundary with another medium. This type of wave pattern is referred to as a traveling wave; for instance, an ocean wave is falling under such category. The wave properties that are described by the following quantities are interrelated. 1. Amplitude: The amplitude of a wave is the maximum displacement of a particle from its equilibrium position as the wave passes through it (see Figure 1.3). It is measured in meters (m). amplitude y x λ FIGURE 1.3 : Amplitude pattern. 2. Frequency: The number of cycles per unit of time is called the frequency, ν , of oscillations caused by the wave. The unit of frequency is hertz (Hz; cycles per second). The quantity ν = ω 2 π = 1 T (1.1) Introduction to Waves and Oscillations 11 where ω is the angular frequency, which is 2 π times the frequency, ν , and T the period of the vibrations; one complete cycle of the wave is associated with an angular displacement of 2 π radians. The angular frequency, ω , of a wave is the number of radians per unit of time at a fixed position. 3. Path difference: The path length, l , is the distance through which a wavefront recedes when the phase increases by δ and is expressed as l = v ω δ = λ 2 π δ = λ 0 2 πn δ (1.2) where v is the velocity, λ the wavelength, λ 0 the wavelength in free space (vacuum), n = c v (1.3) the refractive index for refraction from vacuum into that medium, and c the speed of light in free space.
eBook - PDFElectronic Properties of Crystalline Solids
An Introduction to Fundamentals
- Richard Bube(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
Chapter i Classical Waves: A Review O n e of the unifying themes that runs t h r o u g h o u t physical p h e n o m e n a of m a n y different kinds is that of wave motion. S o u n d waves a n d light waves are part of the subject matter of classical physics, a n d a classical type of wave mechanics is sufficient for at least a partial treatment of the interaction of these kinds of wave with crystalline solids. M a n y of the properties of these classical wave systems are found also in a variety of forms in q u a n t u m wave mechanics. It is primarily for this reason that we begin with a brief review of the classical treatment of waves suitable for a partial description of sound a n d light. 1.1 General Properties of Waves A wave is any periodic disturbance in time a n d position, characterized by a velocity, a wavelength, a n d a frequency. Such a disturbance m a y have quite a general distribution in space as long as these characteristics are definable. T h e relationship between velocity, wavelength, a n d frequency is ν = λν (1.1) Values of these parameters vary widely for different types of wave. Representative values are indicated in Table 1.1. O n e of the simplest a n d most analytically useful wave forms is that of a h a r m o n i c wave which can be represented in terms of sine a n d cosine functions. A n y general wave form can be expressed in terms of a Fourier 1 2 / Classical Waves: A Review T A B L E 1.1 TYPICAL VALUES OF W A V E PARAMETERS Ψ Velocity, ν (cm/sec) Wavelength, λ (cm) Frequency, ν (sec -1 ) Sound (in air) 3 χ 10 4 1 to 3 χ 10 3 10 to 2 χ 10 4 Visible light (in vacuum) 3 χ 10 10 4 x 10 5 to 7 x 10 5 10 15 Free electron (300°K) 5 χ 10 6 8 χ 10-7 6 x 10 12 expansion of ha rmo n i c waves. A h a r m o n i c wave can be expressed mathe-matically in the following kinds of relationship between the displacement ξ, the angular frequency ω = 2πν, and the wavenumber k = 2π/λ.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Learning Press(Publisher)
________________________ WORLD TECHNOLOGIES ________________________ Chapter- 3 Fundamental Physics Concepts 1. Wavelength Wavelength of a sine wave , λ, can be measured between any two points wi th the same phase, such as between crests, or troughs, or corresponding zero crossings as shown. In physics, the wavelength of a sinusoidal wave is the spatial period of the wave – the distance over which the wave's shape repeats. It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns. Wavelength is commonly designated by the Greek letter lambda (λ). The concept can also be applied to periodic waves of non -sinusoidal shape. The term wavelength is also sometimes applied to modulated waves, and to the sinusoidal envelopes of modulated waves or waves formed by interference of several sinusoids. ________________________ WORLD TECHNOLOGIES ________________________ Assuming a sinusoidal wave moving at a fixed wave speed, wavelength is inversely proportional to frequency: waves with higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths. Examples of wave-like phenomena are sound waves, light, and water waves. A sound wave is a periodic variation in air pressure, while in light and other electromagnetic radiation the strength of the electric and the magnetic field vary. Water waves are periodic variations in the height of a body of water. In a crystal lattice vibration, atomic positions vary periodically in both lattice position and time. Wavelength is a measure of the distance between repetitions of a shape feature such as peaks, valleys, or zero-crossings, not a measure of how far any given particle moves.
No longer available |Learn more- (Author)
- 2014(Publication Date)
- Academic Studio(Publisher)
Wavelength is commonly designated by the ________________________ WORLD TECHNOLOGIES ________________________ Greek letter lambda (λ). The concept can also be applied to periodic waves of non -sinusoidal shape. The term wavelength is also sometimes applied to modulated waves, and to the sinusoidal envelopes of modulated waves or waves formed by interference of several sinusoids. Assuming a sinusoidal wave moving at a fixed wave speed, wavelength is inversely proportional to frequency: waves with higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths. Examples of wave-like phenomena are sound waves, light, and water waves. A sound wave is a periodic variation in air pressure, while in light and other electromagnetic radiation the strength of the electric and the magnetic field vary. Water waves are periodic variations in the height of a body of water. In a crystal lattice vibration, atomic positions vary periodically in both lattice position and time. Wavelength is a measure of the distance between repetitions of a shape feature such as peaks, valleys, or zero-crossings, not a measure of how far any given particle moves. For example, in waves over deep water a particle in the water moves in a circle of the same diameter as the wave height, unrelated to wavelength. Sinusoidal waves In linear media, any wave pattern can be described in terms of the independent propagation of sinusoidal components. The wavelength λ of a sinusoidal waveform traveling at constant speed v is given by: ________________________ WORLD TECHNOLOGIES ________________________ Refraction: when a plane wave encounters a medium in which it has a slower speed, the wavelength decreases, and the direction adjusts accordingly. where v is called the phase speed (magnitude of the phase velocity) of the wave and f is the wave's frequency. In the case of electromagnetic radiation—such as light—in free space, the phase speed is the speed of light, about 3×10 8 m/s.
eBook - PDF- Md Nazoor Khan, Simanchala Panigrahi(Authors)
- 2017(Publication Date)
- Cambridge University Press(Publisher)
2 The waves move with a velocity depending upon the properties of the medium. The waves remain stationary and do not move. 3 Each particle of the medium executes periodic motion about their mean position with the same amplitude. Except the node, all the particles of the medium execute SHO with varying amplitude. 4 There is a continuous change of phase from particle to particle. All the particles between two consecutive nodes are at the same phase, but differ in phase by p from those in the preceding as well as succeeding similar segments. 5 At any instant all the particles do not come together in the mean position, they pass their mean position in succession but with the same velocity. All the particles pass their mean position at a time, but with different velocities. Oscillations and Waves 57 6 Each particle of the medium undergoes similar change of pressure and density There is no change of pressure and densities at the antinodes while there is maximum change of pressure and densities at the nodes. 7 There is transmission of energy across every plane in the direction of propagation of waves. There is no flow of energy across any plane. 8 A complete wavelength contains a compression and rarefaction in the case of longitudinal waves and crest and trough in the case of transverse waves. The wavelength is the distance between two alternate nodes and anti nodes. 9 Compression and rarefaction move from point to point throughout the medium. The compression and rarefaction do not move from point to point; they simply appear at and disappear at certain equidistance fixed points. 10 No particle of the medium is permanently at rest.
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