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. M

    Formula for calculating wavelength of sound waves in interference?

    The values calculated was nowhere near the theoretical values, though I guessed they won't be as the results recorded was incredibly inaccurate. My teacher acknowledged the fact the final values won't be close to the theoretical ones but also said that my formula was wrong, that it works to find...
  2. D

    I Planck's law in wavenumber vs. wavelength

    I have asked this question elsewhere. I have gotten no clear answer. What I already know: The interval (differential) sizes (areas) are different in terms of wavelength and wavenumber. The total energy is the same when the curves are integrated over all wavelengths or wavenumbers So please...
  3. Saptarshi Sarkar

    Uncertainty in wavelength and position

    In my attempt to solve the problem, I used the formula for de-Broglie wavelength ##p=\frac h λ## and differentiated both sides to get ##Δp = \frac {hΔλ} {λ^2}##. Plugging this equation into the Heisenberg's position and momentum uncertainty principle formula and calculating the minimum...
  4. S

    Wavelength of the red colour of this helium discharge tube

    Red has the longest wavelength compared to the two other colours so the location of red will be at point C. x = 11.5 cm L = 30 cm d = 1870 nm Putting all into the formula, I get λ = 717 nm Where is my msitake? Thanks
  5. R

    A question related to de Broglie wavelength and the Uncertainty Principle

    "Now, if an electron has a definite momentum p, (i.e.del p = 0), by the de Broglie relation, it has a definite wavelength.A wave of definite (single) wavelength extends all over space. By Born’s probability interpretation this means that the electron is not localised in any finite region of...
  6. S

    Wavelength used in double slit experiment

    m × lambda for bright = (m - 1/2) × lambda for dark so: 2 × 708 = 2.5 × second lambda Second lambda = 566.4 nm But the answer is 495 nm. Where is my mistake? Thanks
  7. S

    I How to calculate the wavelength of light coming from 1 light year away

    How to calculate the wavelength of light coming from 1 light year away. Is there any formula for it. Please help.
  8. jisbon

    Optics (dealing with 2 sources of wavelength)

    To start off, I dealt with questions similar to this, but it only involves one wavelength. Now that there's 2 wavelengths, I'm kind of stumped as to what I should do. Since the question stated a second dark fringe, I can assume that it will be a destructive interference. Since the rays are...
  9. AngelFis93

    Minimum wavelength of phonons under the Debye aproximation

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  10. E

    When does the wavefunction wavelength equal the De Broglie wavelength?

    For instance, in the case of the infinite square well, the wavelength of the wavefunction is \frac{2L}{n}. This also turns out to be the De Broglie wavelength, and and we can find the possible energies directly from the Schrodinger equation, or by using the De Broglie relations. However, if the...
  11. dom489

    How can I increase the wavelength of light photons?

    Summary:: need to increase the wavelength of light. I am an intro physics student working on a project and need to increase the wavelength of photons. I only have visible light sources available but need to have an emission of a wavelength larger than 1mm. is there a way to shift wavelength...
  12. A

    How Do You Calculate the Tension of a Cello String?

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  13. Addez123

    Find Wavelength of Light Wave for Optimal Constructive Interference

    The green ray is moved upwards for clarity, they are all on same x-axis with no y component. Theres a phaseshift at both reflections of the green light because n1 and n3 are > n2. This results in a complete wavelength phaseshift, aka no impact on the wave. That means that only the extra travel...
  14. KiwiJosh

    Wavelength to Frequency Relationship in Musical Notes

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  15. B

    Relating Uncertainty in Time to Uncertainty in Wavelength

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  16. S

    B Can a wavelength be smaller than a Planck length?

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  17. M

    I Typical Wavelength vs Wave Length

    What are the differences between "Typical wave length" and "Wave length" ?
  18. A

    Converting between wavenumber and wavelength

    By dimensional analysis, we have that the wavenumber: $$k = \frac{\text{radians}}{\text{distance}}$$ And the wavelength: $$\lambda = \frac{\text{distance}}{1 \text{wave}}$$ Then: $$\lambda k = \frac{\text{radians}}{\text{distance}}\frac{\text{distance}}{1 \text{wave}} = \frac{\text{radians}}{1...
  19. I

    I What would happen if wavelength could go higher than gamma rays

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  20. E

    Shift in wavelength of photons from the Sun using energy argument

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  21. nineteen

    Does speed of light depend on the wavelength or frequency of it?

    I heard that the speed of light doesn't depend on the wavelength or frequency of it, how does it happen? I don't understand it because the ultimate equation is c = fλ (where c is the speed of velocity of light, f is the frequency and λ is the wavelength of it...).
  22. frostysh

    B Help with understanding the Doppler effect

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  23. J

    How to Solve a Doppler Effect Problem with a Moving Vehicle and Siren at Rest

    Pretending the siren is at rest in air: Wavelength = velocity/frequence --> (343 m/s) / 10,000 Hz = .0343m. I don't believe this is the correct way to go about solving the problem, since the vehicle is moving at the start and the siren is not at rest.
  24. M

    Sensor to Measure Differences in Light Wavelength

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  25. T

    Understanding Waveform & Autocorrelation in Pulse Lasers

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  26. Iskak

    Double slit experiment wavelength of light used

    0.8m -> 800mm λ = (0.4mm*1.1mm)/800mm = 0,00055mm is it right? I am past that 3 months ago, forgot how to solve.
  27. A

    I Does the Compton wavelength put a limitation on position measurements?

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  28. DPMF6973

    Index of refraction and wavelength

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  29. liroj

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    How precise can a wavelength of photons be measured and how much can it vary? For example, 300nm, 300.1nm, 300,11nm, 300.111 etc... What is the limit up to which we can measure it or is there a point where there is no variation anymore - something like a "quantum" of wavelength? Hope you...
  30. P

    Finding Broglie wavelength after acceleration

    KE = 100eV x (1.6x10^-19) v(new) = √(2KE/9.1×10^-31 ) = 5.9x10^6m/sv(original) = h/λm = 6.6x10^-34 / (0.2x10^-9 x 9.1x10^-31) = 3.64x10^6m/s
  31. M

    I What does the term "Typical Wavelength" mean in this context?

    This paragraph taken from a book : What does it mean the typical wave lenght?
  32. JosephTraverso2

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    Homework Statement Hi Everyone, So I'm doing writing up my weekly physics lab report and I had an idea to better present my findings. I have a chart displaying the frequencies of numerous tuning forks as well as their experimentally determined wavelengths and I have to find the speed of sound...
  33. N

    What is the observed wavelength of the Hα line?

    Homework Statement A star moves away from us at a speed of 10 km / s. the angle between the speed direction and the line of sight are 30 °. What is the observed wavelength of the Hα line? Then we suppose the observer is also moving at a speed of 20 km / away from the star. What is the observed...
  34. Rafiki

    [Compton scattering] Solving for wavelength

    Homework Statement Question: Determine the energy of the incident photon when the recoiled electrons energy is measured to 3 MeV. The angle between the incident photon and the scattered photon is 60°. Given and knowns: θ=60° (Angle between incident photon ##\gamma## and scattered photon...
  35. J

    Can the wavelength of a single photon be measured?

    Is there any way to accurately measure the wavelength of a single, individual photon? How precise could such a measurement be? I will be satisfied if the "measurement" consists only of confirmation that a photon from a monochromatic source has the expected value, as long as it has sufficient...
  36. laurieke

    Wavelength of light in a dielectric material

    Homework Statement In a physics lab, light with a wavelength λ0 travels in vacuum from a laser to a photocell in a time t1. When a slab of glass with a thickness d is placed in the light beam, with the beam incident along the normal to the parallel faces of the slab, it takes the light a time...
  37. H

    Transition energy estimation based on bond length

    I come across this question in a textbook. Somehow my result is way off from the solution answer. I used the energy formula for particle in a box with n(Initial) = 22 and n(End) = 23, the calculated box length is 732 pm. I arrived at an answer of 39.3 nm. The answer from the answer book is but...
  38. Krushnaraj Pandya

    Apparent wavelength in Doppler's effect

    Homework Statement a source of sound of frequency f emits sound with speed v, is at rest. If an observer is moving at towards source with speed u, then wavelength of sound waves observed by the observer will be? Homework Equations f' = f(u+v)/u...(i) f' is apparent frequency, f is the real...
  39. L

    Calculating the wavelength of a surface wave after impact

    Homework Statement There's a bucket, filled about halfway with water. The water itself is completely still. A perfect sphere with mass m and volume v are given. The depth of the water, and the radius of the bucket (which may be considered perfectly cylindrical) are both given. In short, you...
  40. Drugstore Cowboy

    I Solar spectral intensity per wavelength - frequency

    Why is solar spectral intensity per wavelength different than solar spectral intensity per frequency?
  41. Penguin98

    The thickness of glass and the longest wavelength

    Homework Statement In your research lab, a very thin, flat piece of glass with refractive index 2.00 and uniform thickness covers the opening of a chamber that holds a gas sample. The refractive indexes of the gases on either side of the glass are very close to unity. To determine the thickness...
  42. C

    De Broglie wavelength of an electron

    I'm reposting this thread with some editing suggested by fresh_42: 1. Homework Statement Calculate the mass, velocity and the de Broglie wavelength of an electron and an alpha particle, given the kinetic energy K = 2MeV Homework EquationsThe Attempt at a Solution please find attached![/B]...
  43. YoungPhysicist

    I Wavelength approaching the Planck length

    If I heat up an object,the object emits a electromagnetic wave with a shorter and shorter wavelength. But if I heat an object up to Planck temperature, and making the EM wave that it emits has a wavelength of Planck distance,what will happen when I heat it up even more? Will the wavelength...
  44. A

    Why is solar radiation equal to long wavelength emission?

    In my heat transfer course, I always had to do analysis of long-wavelength radiation between surfaces first, and find the heat radiated from one of the surface. Then, solar radiation is added to the problem, and suddenly it was said that solar radiation=heat radiated from this surface! Does...
  45. rpthomps

    Wavelength of light changing in a medium

    Good afternoon, I have read that light changes it's wavelength when it enters a different medium because it's speed changes but then I read that the speed of light doesn't change (it's always c) and it just takes longer. So, it is the "observed" wavelength that changes or some such? Any help is...
  46. YMMMA

    Calculate the wavelength when electron transits.

    Homework Statement A photon of wavelength 300nm is emitted from an atom when an electron makes a transition from an energy state of -4 eV to a state of -8 eV. IF the initial state had been at enerygy of -6 eV, the wavelength of the photon emitted in a transition to -8eV is..?? Homework...
  47. T

    Wavelength of a laser within an optical cavity

    1. The problem statement, all variables and given/known date Homework Equations $$\delta v=\frac{c}{2nL} \:[1]$$ $$N=\frac{\Delta v}{\delta v}=\frac{2nL\Delta v}{c} \:[2]$$ The Attempt at a Solution I am having trouble with question 5, but have come to realize I think my cavity length is...
  48. J

    I Particle creation, energy density and the Compton wavelength

    The Compton wavelength of a particle is given by $$\lambda=\frac{h}{mc}.$$ One can construct an expression for the energy density ##\rho## of a particle of mass ##m## given by $$\rho = \frac{mc^2}{\lambda^3}=\frac{m^4 c^5}{h^3}.$$ What is the physical significance of the mass scale ##m## in the...
  49. Samuel Williams

    Determine the Transition Wavelength

    Hi all, the question is as follows: 1. Homework Statement From the energy level diagram for OH in the study guide, it can be seen that the first rotationally excited level of OH (2∏3=2 J =5\2) lies 120 K above the groundstate. What is the wavelength of radiation associated with a transition...
  50. S

    Peak wavelength and Spectral Bandwidth

    Homework Statement Calculate the expected peak wavelength and spectral bandwidth (in units of wavelength) of the emission for both a GaAs and silicon LED at liquid nitrogen temperature (77 K) and room temperature (300 K). Which of these cases would you expect to result in the best emitter and...
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