Wavelength Definition and 1000 Threads

In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, troughs, or zero crossings, and is a characteristic of both traveling waves and standing waves, as well as other spatial wave patterns. The inverse of the wavelength is called the spatial frequency. Wavelength is commonly designated by the Greek letter lambda (λ).
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 of the wave: waves with higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths.Wavelength depends on the medium (for example, vacuum, air, or water) that a wave travels through. Examples of waves are sound waves, light, water waves and periodic electrical signals in a conductor. A sound wave is a variation in air pressure, while in light and other electromagnetic radiation the strength of the electric and the magnetic field vary. Water waves are variations in the height of a body of water. In a crystal lattice vibration, atomic positions vary.
The range of wavelengths or frequencies for wave phenomena is called a spectrum. The name originated with the visible light spectrum but now can be applied to the entire electromagnetic spectrum as well as to a sound spectrum or vibration spectrum.

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  1. A

    Wave: amplitude, frequency, wavelength

    Homework Statement Original question: A boy flicked a string harder, describe the changes of the waveform and the speed of the wave. Homework Equations V = f x λ Frequency is how many completed oscillation per second. Wavelength is distance between two adjacent points of the same...
  2. Spinnor

    Fields of a very short laser pulse, pulse a fraction of wavelength.

    Scientists can produce laser pulses of order one wavelength in "length" see, http://www.bbc.co.uk/news/science-environment-19489384 Do Maxwell's equations admit solutions of such short pulses? Can one approximate such a solution by multiplying a plane electromagnetic wave by the...
  3. K

    Wavelength of New Laser with Diffraction Grating Measurement

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  4. Q

    Photon Flux per Unit Wavelength

    Hi How do you get a photon flux per unit wavelength curve for solar radiation? My understanding of "per unit wavelength" is that the wavelengths within a very short range are fired at a detector. The range is then gradually changed to cover higher wavelengths. The values of flux measured by...
  5. F

    Wavelength Speed: 10nm vs 1mm - Does UV Travel Faster?

    Would light at 10nm be traveling at a slower speed due to having to go a shorter distance than light at 1mm? The IR light is traveling a straighter line to its destination than the UV so for both of them to arrive at the same time the UV must be going faster in order to make up time and be at...
  6. E

    Wavelength of scattered photon and angle of scattering in the Compton scattering

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  7. E

    Threshold frequency and wavelength of electrons in the photoelectric effect

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  8. A

    Flux Density (Jy) to Luminosity when wavelength is involved

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  9. S

    De broglie wavelength and lorentz contraction

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  10. H

    Visible light wavelength discrepancy on the EM spectrum?

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  11. C

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  12. B

    Help understanding solar imaging wavelength and coronal temp

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  13. T

    Is there any relation between wavelength and brightness?

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  14. T

    De broglie wavelength of fast moving particle-help please

    De broglie wavelength of fast moving particle--help please! Homework Statement A particle moving with kinetic energy equal to its rest energy has a de Broglie wavelength of 1.7898 *10^-16 m. If the kinetic energy doubles, what is the new de Broglie wavelength? Homework Equations...
  15. K

    De Broglie wavelength from scattering of neutrons on crystal

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  16. S

    What are phasors and how do they relate to determining the wavelength of a wave?

    Homework Statement My physics text states: "We can represent a string wave (or any other type of wave) vectorially with a phasor." Now, for phasors the amplitude and angular frequency are given. If this is the case though, how is k, the angular wave number (and hence the wavelength)...
  17. P

    Determining Maximum Wavelength of Incident Radiation

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  18. M

    How Does de Broglie Wavelength Affect Particle Behavior in Helium Gas?

    The atoms in a gas can be treated as classical particles if their de Broglie wavelength is much smaller than the average separation between the particles. Compare the average de Broglie wavelength and the average separation between the atoms in a container of monatomic helium gas at 1.00 atm...
  19. X

    Wavelength of Particle Passing Through Potential Barriers

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  20. A

    What is the wavelength of the light？

    Calculate the wavelength of the light emitted when an electron in a one-dimensional box of length 5.2nm makes a transition from the n = 7 state to the n = 6 state. Express your answer with the appropriate units. I calculated in this way: E = n^2*h^2/8*m*a^2 E=...
  21. V

    Confused about definition of wavelength

    Wavelength of a sinusoidal wave is defined as the spatial period of the wave, which can be measured between any two points on the wave where the shape repeats. But if my wave is defined as a function of time (like those of a simple harmonic oscillator), how can you say the distance along the...
  22. S

    Electron Wavelength in Infinite Potential Well

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  23. C

    Increase in Wavelength of an LED Immersed in Liquid Nitrogen

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  24. P

    Wave Nature of Light - Calculating Wavelength (Double Slit Exp)

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  25. A

    Momentum of a proton in de Broglie wavelength

    Homework Statement In quantum mechanics the de Broglie wavelength of an object depends on its momentum according to λ=h/p where h is Planck's constant. Protons of charge e and mass m are accelerated from rest through a potential V. What is their de Broglie wavelength? A) 2h/\sqrt{}meV...
  26. G

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  27. C

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  28. C

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  29. C

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  30. D

    Electrons motion at de broglies wavelength

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  31. Z

    Archived How Do You Calculate the Wavelength of an Electron with 1keV Kinetic Energy?

    Homework Statement Homework Equations de Broglie wavelength λ = h/p E^2 = p^2 c^2 + (m0)^2 c^4 L-compton = (h-bar) / mc The Attempt at a Solution I'm trying to work out the wavelength of an electron with a kinetic energy of 1keV So I intend on using de Broglie...
  32. K

    Solving Phase Change & Spatial Separation with Wavelength & Velocity

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  33. A

    Light wavelength passing through a grating sketch help

    Homework Statement light with a wavelength of 520 nm abd 630 nm passes through a diffraction grating that contains 6000 lines/cm. a) sketch a diagram of the image produced from m=0 to m=2, label the order of each fringe b) calculate the angles for the first and second order maxima that...
  34. Z

    De Broglie wavelength and Fermi wavelength

    As we know that the properties of nanoscale material are quite diffrent from the bulk's. But what's the threshold of the size, or what the upper limmit where significant difference can be observed? The De Broglie wavelength or the Fermi wavelength of the electron in material? How to understand that?
  35. K

    Find sound wavelength from a vibrating string

    Homework Statement Sound Wavelength From String During a concert a pianist hits a key that sets up a standing wave in a piano string that is vibrating in its fundamental mode. The string is 0.5 m long, has a mass density of 0.002 kg/m and is held under a tension of 120 N. What is the wavelength...
  36. S

    What is the Wavelength of Earth and its Impact on the Macroscopic World?

    I got this from my grade 12 physics notes. It says that Earth, having a mass of 6.0x10^25kg and a speed of 3.0x10^4 m/s, when plugged into the wavelength equation λ=h/(mu) (where u is speed), has a wavelength of 4x10^-63 m. Then, does this mean it has a frequency of 7.5x10^70 Hz? If so, then...
  37. S

    De Broglie Wavelength Calculation for an Electron with KE= 8.5 eV

    Homework Statement What is the De Broglie wavelength of an electron with KE= 8.5 eV? Homework Equations λ=h/p KE=0.5mv2 p=mv The Attempt at a Solution I converted 8.5 eV into joules: 8/5 eV × 1.602e-19 J = 1.3617e-18 Then used it for KE to solve for v: I got 1729006.11...
  38. L

    DeBroglie wavelength in infinite potential well

    nvm i figured it out. it was not in reference to n=4. equation used would be wavelength = 2L/n Homework Statement An electron is in an infinite potential well of width L. Which is not an allowed deBroglie wavelength for the electron to have when n=4? wavelength(k) = 3L, 2L, L/2, or L/3Homework...
  39. R

    The de Broglie wavelength of molecules

    Homework Statement http://img580.imageshack.us/img580/7492/50177994.jpg The Attempt at a Solution I first attempt part (a) since both parts are similar: (a) I need to know "v" in order to use the following equation to find the de Broglie wavelength: \lambda = \frac{h}{p}...
  40. J

    Long vs Short light wavelength absorption

    Hi all I was reading through an astrophysics book{1} and there I came across this sentence: " A dust cloud can either scatter or absorb light that passes through it. Since shorter wavelengths are affected more significantly than longer ones, a star lying behind the cloud appears reddened...
  41. A

    Double slits experiment, wavelength calculation

    Homework Statement In a double slit experiment with slits 1. 10-5 m apart, light casts the first bright band 3.10-2 m from the center of a screen 0.65 m away what is the wavelength ? Homework Equations dsin(theta) = (m +1/2)lambda, The Attempt at a Solution I think to solve...
  42. A

    Change in wavelength, photon hits a free electron.

    Homework Statement A photon with initial momentum p collides with a free electron having a mass m that is initially at rest. If the electron and photon recoil in opposite directions, what will be the change in the photon’ wavelength? (Hint: use relativistic forms for energy and momentum.)...
  43. H

    Size of a waveguide for a given wavelength

    Let λ be the wavelength of an EM wave in empty space. Let a x 0.5*a be the dimensions of the cross-section of the waveguide. Can I use a = 0.35*λ ? It should be possible, it corresponds to θ = π/4, where θ is the effective angle between the long axis of the waveguide and the direction of...
  44. M

    Debroglie Wavelength: λ & v Proportional?

    According to Debroglie Eq λ=h/mv λ and v inversely proportional to each other.But according to eq v=f*λ they seem to be directly proportional.So what is the actual dependence of lambda on v?
  45. M

    Optical modulator wavelength dependency

    What is the effect of using other than 1550nm light with an (LiNbO3, lithium niobate) electro-optic Mach-Zehnder modulator? Thanks!
  46. J

    How does wavelength change with speed?

    I thought I heard the fact that when you make a particle faster it's wavelength get's bigger, and if we accellerate a baseball enough it's wavelength goes visible? but is that just a misunderstanding and opposite... because one can see in the broglie wavelength equation: λ = h/mv that...
  47. J

    How close must the wavelength of a photon be for an atom to absorb it?

    When a photon has a wavelength close to the energy needed for an electron jump in an atom, the atom will absorb the photon. How close must the wavelength be to the energy required for the atom to still absorb it?
  48. V

    Dependance of radiation properties on wavelength

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  49. Q

    Light, Wavelength, Space, and the color of Stars

    Question 1: http://i.minus.com/iOmQvqhasiXmx.png My reasoning is curves 3 and 4. These curves have the biggest relative brightness of orange. Question 2: Stars are called blackbody radiators because they a) never appear perfectly black b) always appear perfectly white c)...
  50. edpell

    De Broglie wavelength and direction

    We can calculate a de Broglie wavelength for a particle with momentum p. My question is does this apply to the lateral size of the particle? Perpendicular to the motion the momentum is zero. What can we say about the size of the particle in the perpendicular direction?
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