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. P

    Broglie wavelength - calculate electric potential difference

    Homework Statement In a TV tube, an electric potential difference accelerates electrons from a rest position towards a screen. Just before striking the screen, the electrons have a wavelength of 1.0 x 10^{-11} m . Find the electric potential difference.Homework Equations λ = h/mv ΔE_k = qΔV...
  2. A

    Finding the frequency and wavelength of an electromagnetic wave

    Homework Statement Homework Equations The Attempt at a Solution Do I set up a proportion to first find the frequency of the electromagnetic wave in glass? 1.33/(3.42*1014)=1.62/fglass= 4.17*1014
  3. P

    How Do You Calculate Wavelength from Frequency?

    I don't remember the question exactly because I saw it in my final exam and I'm confused and don't know how to solve it exactly, so here's the question: 99 MHZ (99000000 HZ) frequency is produced to a 60 m base, find the wavelength. They didn't mention neither the velocity nor the time, and I...
  4. H

    Question: Calculate Wavelength from Intensity

    Homework Statement Question: Calculate the wavelength in mm of the most intensive microwaves Question before: State the intensity of the most intensive microwaves detected Answer: 380 Units. (5 Waves per CM) [Read from a graph] Homework Equations None given. The Attempt at a Solution I...
  5. C

    Detection of a Specific Fluorescent Wavelength via iPhone camera

    So in my lab, I am working with fluorescent bacteria, specifically GFPa1 (green fluorescent protein a1) which are excited with around 500nm light and emit around 516 nm. Forgive me if these aren't correct, it isn't essential for this write-up and my notes aren't in front of me. Is there any way...
  6. D

    Describe the pattern of intensity vs wavelength .

    Describe the pattern of intensity vs wavelength observed in blackbody experiments and explain why these observations were in conflict with the predictions of classical physics. is this right? the shorter the wavelength, the greater the intensity. This is wht I wrote: Classical...
  7. G

    Wavelength Diagram: Difference in Intensity Blueshift vs Redshift

    Hey I have to find a diagram that shows the difference in wavelength intensity between a blueshift and a redshift. I've searched for a while but all the diagrams I find are pretty awful. If anyone knows any that decent ones would you mind linking it below? All I can find is the colour...
  8. S

    Image Processing: Exploring Wavelength, Intensity & HSV/RGB

    I was working on an image processing project a while ago and was specifically working with raster images in the Hue-Saturation-Value(HSV) image format. Each is determined by mathematical values of these (HSV) parameters. I also worked with other bases such as the Red Blue Green (RGB) format. Now...
  9. S

    Change in speed and wavelength of light while travelling from one med

    what is the mechanism by which light changes its speed and wavelength while traveling from one medium to other. I know it is c/n or lamda/n and know it comes from maxwells equations, but what is the physical reason behind this?
  10. K

    Antenna Wavelength - double-slit interference

    Homework Statement The question is " Two large boulders lie between the house and Farmer Joe's favorite radio station. Farmer Joe cannot put the antenna on his house because the howl of the wind through it keeps Mrs Joe up all night. Where is the next best place Farmer Joe can put his antenna...
  11. A

    Focal length multiplied by wavelength

    Simple question: is there any physical significance of the quantity (focal length of lens)*(wavelength of laser light passing through the lens) ? How does it relate to the size of an image on the image plane? According to my professor, (focal length)*(wavelength)/(constant) is the length of...
  12. J

    To which natural frequency does wavelength equal to L1

    Homework Statement The length L1, is not the wavelength of the fundamental frequency of the string. With the tension equal to F1, to which natural frequency does the wavelength equal to L1 correspond? Homework Equations I was reading online, and found that when a string vibrates at...
  13. D

    De Broglie Wavelength: What Is It and How Does It Affect Us?

    Before i understood that the de Broglie wavelength gets smaller as the momentum increases of an object, so my think was that because our (human body) momentum is so large that the de Broglie wavelength would be so small for there to be any effect on us, i know that we are also to large to...
  14. R

    [SolidState] Highest wavelength to excite an electron in CdTe

    I'm reading through old exams, but there's not very much in the way of explanation, and this is one of the problems I have that I'm not sure that I fully understand. We have the material CdTe. What is the highest allowable wavelength that incoming light can have in order to excite an electron...
  15. M

    Calculate the wavelength of an electron for a certain energy

    Got a hmwk question here that asks to calculate λ of an electron with a certain amount of energy, and sadly couldn't figure it out. My solns manual does a fantastic job of regurgitating the formula: E = P2 / 2m0 to be used to get the numerical soln which is technically all I need but I'm...
  16. S

    Doppler Effect Question regarding wavelength changing

    Homework Statement A listener L hears the siren from a moving police car ,S, which is moving away from the listener with a speed of v = 20.0 m/s. The listener is moving at 10.0 m/s towards the car. There is a wind blowing with a speed of v(wind)= 10.0 m/s from S to L. The siren is emitting...
  17. M

    Unraveling the Mysteries of Intensity vs Wavelength

    I am really confused about this! So people thought that as wavelength increases for electromagnetic radiation, intensity of radiation increases but this would mean that people would melt if exposed to any radiation higher than visible light. But then they did an experiment and they sketched the...
  18. L

    Photon Wavelength: Particle or Wave?

    I understand that electromagnetic radiation is a photon. But one thing that is continuing to bug me is the question how does a photon, which is defined as a particle not a wave, have a wavelength? Do photons travel as packets in some sort of a compression type wave similar to sound?
  19. J

    What is wavelength of light a measure of?

    Is it the wavelength of the electric portion or magnetic portion or something else entirely?
  20. E

    Bragg Law and Effect of Doubling Wavelength

    My lecturer discussed bragg's law a few weeks ago and described how the angle theta changes as the wavelength is doubled. I can't seem to duplicate his result. I know that the bragg condition for a maxima would reduce to : dsinθ=mλ when the wavelength is doubled. In his example he knew...
  21. O

    Photon wavelength probability distribution for blackbody

    Hey everyone, This is my first time posting on PF! I want to model the photons ejected from a blackbody source at temperature T. The question I want answered is: given a photon is detected, what is the probability of the photon having a wavelength λ? This amounts to just attaining the...
  22. J

    Can you change the wavelength of ligh without changing it's direction?

    So let's say we have a red light wave, can you have something particularly simple amplify it's wavelength, I know you could take a picture of it and send it out again the opposite side, but that's far sought. Oh and if an electromagnetic wave is absorbed by an atom, how exactly do you tell the...
  23. A

    How Can a Lens Microstructure Alter LED Light Wavelengths?

    In my research, I want to make a transparent lens where there will be a microstructure on its surface. This lens will be used to change a wavelength of an LED lighting. Would anyone explain a physics phenomen behind this? Thank you.
  24. A

    How can diffraction be explanined using the concept of wavelength.

    hi.. I have been struggling, since a long time, to understand how is the diffraction pattern obtained by a slit of width of the order of the wavelength of light used is obtained, but found no answers! As per the idea of wave theory (and Fermat's principle) it is the wave nature (specifically...
  25. C

    Max Wavelength of Sodium Ionization

    Homework Statement Atomic sodium is studied by photoelectron spectroscopy. What is the maximum wavelength of the incident radiation that will ionize the most weakly held electrons in sodium and scatter them so that their de Broglie wavelength measures 3.091e-10 m? Homework Equations...
  26. W

    Why do all particles have a wavelength?

    So for my AS specification I need to know how to use the debroile wavelength equation which is fair enough and easy. I was wondering if anyone could tell me why do all particles have a wavelength or wave function? Or even like a tennis ball? Thanks, PS: I know it's a weird question...
  27. iVenky

    Why can't we see objects smaller than wavelength of visible light?

    I read in Feynman's book that it is not possible to see objects less that wavelength of visible light with a microscope. That's the reason why we go for electron microscope. Why can't we objects which is less than wavelength of the information carrying medium (which in this case is visible light)?
  28. dexterdev

    Why in smithchart 360 degree corresponds to half the wavelength

    Hi, Actually wavelength λ corresponds to 360 degrees , right? then why λ/2...
  29. V

    De Broglie wavelength in terms of accelerated potential difference

    Problem: Derive a formula expressing the de Broglie wavelength (in Å) of an electron in terms of the potential difference V (in volts) through which it is accelerated. Solution (so far): The textbook's answer is the following, \lambda=12.27[V(\frac{eV}{2m_{0}c^{2}}+1)]^{-\frac{1}{2}} I'm...
  30. F

    Using recoil of atom to find correct in wavelength of emitted photon

    So firstly, the book supplies the answer of \Delta\lambda = \frac{h}{2mc} I use energy and momentum conservation. I say the total energy is that of the incoming photon, which is then changed to energy of the photon released, and kinetic energy of the atom, from the recoil. I say the same...
  31. V

    Determine X-ray Wavelength & Frequency

    Problem: Determine the wavelength and frequency of the emitted x-rays when 100-keV electrons strike a target. Solution: Assuming all kinetic energy of electrons is used to produce the x-rays, E_initial=E_final K+m_0*c^2=hf+m_0*c^2 K=hf K=hc/λ =>λ=hc/K=(6.63x10^-34 Js)(3.00x10^8...
  32. J

    Why is a photon considered a point particle despite having a wavelength?

    So if an electromagnetic wave can have a wavelength measuring 100 km (an arbitrary measurement of course), why is a photon a point particle. Is it a point, or a varying size maxing out at 100 km? Are the perpendicular magnetic fields spanning 100 km at the peak of the cycle?
  33. PhizKid

    How to find wavelength with only distance

    Homework Statement A metal rod attached to a tube with both closed ends is stimulated to create waves inside the tube. If: L = 1.0 m d = 0.05 m Speed of sound in air = 340 m/s Speed of sound in metal = 1,000 m/s Calculate the value of x using the wavelength of air. Homework Equations...
  34. PhizKid

    Wavelength Problem Homework: 2L or 4L for 0.5m String?

    Homework Statement A uniform string of length 0.5 m. is fixed at one end and free at the other end. Find the wavelength of the fundamental mode of vibration. Homework Equations λ = (2L) / mode The Attempt at a Solution λ = (2(0.5 m.)) / 1 λ = 1 m. But the solution says it's 2...
  35. A

    De Borglie's wavelength equation

    Homework Statement A molecule is 3 nanometers wide and weighs 5 x 10^-15kg. It is fired through a slit that is 5 nanometers wide. Approximately how slow does the molecule have to go so that it diffracts? Homework Equations I'm thinking that I could use De Borglie's wavelength equation...
  36. M

    How to measure the wavelength of a light source

    Hey Folks Quick disclaimer: I have no background in physics whatsoever but I have found myself trying to solve a problem that is seemingly based in physics so I am trying to learn. I also have a background in search and search engine optimisation which usually means I am a dab hand at...
  37. D

    Matter wave - relationship between broglie wavelength, wavelength

    Homework Statement 1. fh stands for energy of a particle. But what is included in the energy ? K.E. of the particle only ? 1.1. If fh is the K.E only, then I have a question. λ=h/p --> fλ=fh/mv --> mv^2 = fh. It is strange that fh = mv^2 but not 1/2 mv^2. 2. Is broglie wavelength equivalent to...
  38. G

    How do you measure Electromagnetic wavelength?

    As we know EM waves have a wave length. Well, how do you measure them? I have the feeling there is a path from point A to point B and that path goes up and down at a regular rate and all photons travel along that wave-path and that they are no where else between A and B but on that path. But...
  39. jaumzaum

    Why the electron orbit is a integer multiple of De Broglie wavelength?

    I cannot understand why the electron orbit should be an integer multiple of De Broglie wavelength. Why should the wave path "fit" the electron orbit for it to be stationary?
  40. R

    Find wavelength, Phase Difference, and amplitude from min and max

    Homework Statement See attached image Homework Equations Δphi = 2pi(Δx/λ) + Δphi0 = 2pi(m) -- at the maximum Δphi = (m + .5) (2pi) -- at the minimum The Attempt at a Solution The first step should be to solve for lambda, the wavelength. So I plug in the knowns: At 30 cm...
  41. Q

    Low Wavelength and Photosynthesis

    I realize this is not a biology forum. Check out the attachment. As expected, plants can use some low wavelength ultraviolet light for photosynthesis. However, the photosynthetic process seems to go nuts when x-rays are used. This is the first time I've ever heard of this. Even gamma rays...
  42. R

    Understanding Body Heat Wavelength: FAQ and Applications

    Can someone explain to me what is the wavelength of body heat? Since visible light is between 400nm - 700nm. Is body heat wavelength above 700nm? What is the wavelength range of body heat in respects to nm or m? And lastly are Infrared cameras made with Avalanche Photo Diodes? like the one...
  43. C

    Wavelength Problem: Compute Frequency in 4m Room

    Homework Statement A room is 4m wide in the x direction, ignore the y and z directions. Compute the longest sound wave that can occur in the room and its frequency.Homework Equations speed of sound = 350 m/s λ = speed/frequency The Attempt at a Solution Since the room is 4m wide and sound is...
  44. P

    De broglie wavelength derived from relativity but used in non relativity?

    The question as stated in title, why?
  45. Q

    Archived How Can You Calculate the Wavelength in a Double Slit Experiment?

    Homework Statement The following data was obtained via the double slit experiment: angle to the eighth maximum = 1.12 degrees distance from slits to screen = 302cm = 3.02m distance from first to fifth mimum = 2.95cm distance between slits = 0.00025m find the wavelength. Homework Equations...
  46. jaumzaum

    Wavelength associated with the body - What does it mean?

    I was studying De Broglie Theory in which all bodies in movement have a de broglie wavelength associated with it. But what it means? The body's speed (Vb) is different from the wave-associated speed (Vw) Vw=λ f and Vb ≠λ f Which wave is that? Is it the wave emitted by the body as it is in...
  47. R

    Calculate the kinetic energy of an electron with a wavelength of 1fm

    Homework Statement Calculate the kinetic energy of an electron with a wavelength of 1fm Homework Equations DeBroglie's relation E^2=(pc)^2+\left(mc^2\right)^2 The Attempt at a Solution I used debroglies relation to find momentum. plugged that into find E, and then subtracted the...
  48. K

    What is the shortest wavelength photon emitted in a hydrogen atom?

    Homework Statement Calculate the shortest wavelength photon that is emitted in the hydrogen atom. Energy when n = 1 = -13.6 eV Homework Equations E = hc/λ λ = hc/E The Attempt at a Solution Well as far as I understand, when the electron is in the n = 1 energy level it has it's...
  49. 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...
  50. 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...
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