What is Wavelength: Definition and 1000 Discussions

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. S

    Refraction of light and wavelength

    Light of wavelength 680 nm in air enters water making an angle of 40 degrees with the normal. Find the angle of refraction and the wavelength of light in water. I found the angle of refraction, but I don't know how to calculate the wavelength with this information.
  2. C

    Hydrogen Emission Spectra Wavelength

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  3. H

    Calculating frequency and wavelength off of a graph

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  4. L

    Debroglie Wavelength Homework: Proton and Alpha Particle Ratio

    Homework Statement The momentum of a proton and an alpha particle are equal. The mass of alpha particle is 4 times the mass of proton. The ratio of wavelength associated with them is ---- Homework Equations \lambda = h / p The Attempt at a Solution if the momentum are equal then...
  5. S

    Finding the max wavelength for two waves to interfere destructively

    Homework Statement i) Two waves travel between two points along paths that have the same length 4.7 x 10^-7 m, one travels in a medium having a refractive index of 3.5 while the other travels through a vacuum, how long does in take for each wave to travel between the points? ii) If the...
  6. N

    How do Heisenberg Uncertainty & de Broglie wavelength apply to atom trap?

    I had this https://www.physicsforums.com/showthread.php?p=3200140#post3200140", which I posted on PF. I got the answer, but then I started thinking more about it and have some theoretical questions. If you did have this particle of mass m in a box of length L, which you are trying to stop...
  7. K

    Which of the following particles would have the shortest wavelength?

    which of the following particles would have shortest wavelength provided that all move with the same kinetic energy? electron, proton, neutron, alpha paricle? My professor said in class that it was alpha particle, but i think its electron... which one is right? and why?
  8. C

    Tensions of string of different wavelength etc

    Homework Statement An A string (s1) from one musical instrument (i1), is replaced by an A string (s2) from a different instrument (i2) (both in the same family) what would be the tension ratio of string 2 after it has been replaced onto instrument 1? string 1 Length of string= 0.37 m...
  9. B

    How Much Kinetic Energy Do Electrons Need to Resolve a 10fm Nucleus?

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  10. B

    Pair production minimal wavelength

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  11. W

    Wavelength of a wave in a closed tube

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  12. B

    De Broglie wavelength, Maximum kinetic energy, and smoke particles

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  13. A

    Why does the angle of light through a prism change based on its wavelength?

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  14. D

    Calculate Resonance Wavelength?

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  15. B

    Calculating Wavelength with Wave Speed and Period | Physics Homework Help

    Homework Statement What is the wavelength λ of a wave that has a speed of 160 m/s and a period of 4.9 ms? Homework Equations λ = vT The Attempt at a Solution λ = 160 x 4.9 = 784m However this answer is showing up as inccorect when I submit it online. What am I doing wrong?
  16. fluidistic

    De Broglie's wavelength problem

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  17. fluidistic

    De Broglie's wavelength, what is it?

    From an exercise I calculated the de Broglie's wavelength of a bullet (mass=40g and speed =1000m/s) to be very small: 1.65651 \times 10 ^{-35}m. What does this mean? That to observe some interference pattern if I throw up these kind of bullets into a double slit, I'd need a width of the slit...
  18. X

    Finding the De Broglie Wavelength of a Hydrogen Atom at Room Temperature

    Question: Calculate the De Broglie wavelength for a hydrogen atom at room temperature (300K). So far, the only equation I know/have used for De Broglie wavelength is lambda=h/(mv). However, I am not exactly sure how to incorporate the information that the hydrogen atom is at room temperature...
  19. J

    Find wavelength for a standing wave

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  20. B

    Wavelength and destructive interference

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  21. S

    Finding wavelength of sound waves

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  22. R

    Help finding de Broglie wavelength for an electron

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  23. A

    How Can You Measure Light Wavelengths Using Microscope Slides and Rubber Bands?

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  24. V

    Very simple problem about wavelength, just a double check on work

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  25. M

    Calculating the 'Wavelength' Of the first harmonic

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  26. V

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  27. L

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  28. morrobay

    E = Em sin(kx-wt) and I = T+R what wavelength is reflected wave

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  29. P

    Quantum, photon, wavelength relationship

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  30. M

    Finding the de Broglie wavelength from momentum

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  31. mishima

    Confused about wavelength (basic)

    I'm confused about how to think about wavelength for something physical, like a simple pendulum or harmonic oscillator. I understand graphically what wavelength is but can't seem to come up with a physical description. I was thinking about ocean waves and that wavelength could be the direct...
  32. D

    Finding the wavelength of this wave

    Homework Statement Okay, here is a photo of the wave I did on a graphing program: http://img221.imageshack.us/i/wavelengthsgraph.jpg/ Now the total distance the wave travels is 4.8 M. There are 3 crests and 3 troughs, but there is only 2 wavelengths throughout the wave. This confuses me...
  33. O

    Calculate wavelength of electron

    Homework Statement http://www.screencast.com/users/trinhn812/folders/Jing/media/9582a1aa-b21a-4e50-8774-b60866a7d666 Homework Equations lambda=h/p The Attempt at a Solution So I got 4.04E-12 m but the book says the answer is 3.23pm I'm not sure where I'm wrong
  34. F

    Wavelength of photon and size of imaged object

    I have read the statement that 'the wavelength of the photons used in imaging an object needs to be much larger than the object itself', although I have never seen/heard a reason explained or the name of a theorem quoted. I have seen this in the description of more than one imaging modalities...
  35. S

    Work function of silver given wavelength

    Homework Statement If electrons can be ejected from a silver surface using light with wavelengths as large as 262 nm. What is the work function for silver? Homework Equations work function=hf c=f\lambda The Attempt at a Solution Given the wavelength, I solved for f =...
  36. T

    Work function of a cathode, when the wavelength of light is increased by 50%

    Homework Statement The maximum kinetic energy of photoelectrons is 3.14 eV. When the wavelength of the light is increased by 50.0 %, the maximum energy decreases to 1.11 eV. What is the work function of the cathode? Homework Equations Kmax = E elec - E not = hf - hfnot hf =...
  37. U

    De Broglie wavelength and mass

    I've been studying quantum physics for a little over a semester now and I'm having trouble wrapping my head around the physical significance of matter waves. The derivation also confuses me because it states the momentum of particle with mass as mc, which is only true for a massless photon. I...
  38. R

    Maximum detectable wavelength of a photoresistor

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  39. A

    De Broglie Wavelength - Can a Person Move Slow Enough?

    Just a random thought: is it not possible for a person to move slow enough to have an observable de Broglie wavelength? For example a person moving at around 10^-30 m/s should have a wave nature that is very observable.
  40. Seanskahn

    Radio communicattion in lower wavelength

    Hi community. Once again, a stupid question: if radio waves are electromagneetic waves, generating an electric field in the antenna, then why can't one just shine visual light (also electrromagnetic waves) on same antenna and use that for communication? thanks s
  41. M

    X-ray Diffraction, Intensity vs. Wavelength Graph

    Homework Statement http://b.imagehost.org/0607/Question_7.png Homework Equations [PLAIN][PLAIN]http://d.imagehost.org/0813/Untitled_6.jpg The Attempt at a Solution I was able to get question b, which ends up being 73pm, but as for questions a and c, I was unable to come up with...
  42. F

    How is the wavelength of monochromatic light measured

    how is the wavelength of monochromatic light measured by using diffraction grating and spectometer?
  43. P

    Finding deBroigle wavelength of a charged electron

    Homework Statement Given an electron with total energy 1 KeV, determine it's deBroigle wavelength. Homework Equations E^2 = (mc^2)^2+(pc)^2 \lambda = \frac{h}{p} The Attempt at a Solution (pc)^2 = E^2 - (mc^2)^2 <> p = ± \frac{1}{c} \sqrt{E^2-(mc^2)^2} What am I doing...
  44. M

    Wavelength of photon in a medium

    A photon goes from vacuum into a medium. This causes its momentum to reduce. Hence by the de Broglie formula, its wavelength should increase. But, since the refractive index of the medium is greater than 1, and n_2/n_1 = \lambda_1 / \lambda_2 , and hence, its wavelength should decrease...
  45. N

    How Do Wi-Fi and Bluetooth Devices Transmit Digital Data?

    Wi-Fi Wavelength?? First of all,, HI, everybody, I am Sonics from India I was searching on Wi-Fi modems and how other bluetooth enabled or wireless things work. I know that they catch some frequency and then convert it to something that is been sent on that wavelength but I don't know that how...
  46. S

    What is the Correct Wavelength of Light in an Interference Experiment?

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  47. S

    Q : Verify Wien's displacement law (frequency and wavelength form)?

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  48. C

    Wavelength and Extinction Coefficients

    I have been researching on the net and books for some time now. I have a few tables and equations but was wondering if anyone has the one I am looking for? I'm looking for a table that lists Wavelength(nm), Extinction Coefficient(k), Absorption Coefficeint(a) and Density(d) values from ~300nm...
  49. E

    Math of De-Broglie wavelength boggles me

    According to simple math you get \lambda=h/p for photons. and the assumption is for everything else, whilst for everything else which is NOT restmass=0 it should be \lambda=hc/E. So why is it referred to as simple \lambda=h/p when clearly it is not true mathematically. It would be true for...
  50. I

    Sub woofers and tweeters wavelength

    [b]1. question [b]2.hello Dear , I have a question for you please , When you buy a home cinema system, you can place the subwoofer almost anywhere, even behind your couch. But the tweeters (speaker for high frequencies) must be placed very accurately. Explain why! Hint: use...
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