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. B

    Real component of the wavelength of microwaves in copper

    I am trying to work out the real component of the wavelength of microwaves in copper. I am given n2=er=-i sigma/eo omega where n is the refactive index er is the relative permitivity eo is the permitivity of free space i = sqrt(-1) omega is the frequency of the microwave sigma is the...
  2. F

    Calculating Slit Width Using Microwave Wavelength

    Homework Statement Microwaves of wavelength 2.80 cm fall on a slit and the central maximum at a distance of 1.0 m from the slit is found to have a half-width (i. e. distance from middle of central maximum to first minimum) of 0.67 m. Find the width of the slit.
  3. fluidistic

    What Are the Key Distances in a Double Slit Experiment with 632.8 nm Light?

    Homework Statement A extent ray of light with wavelength \lambda _0=632.8 nm incide over a screen containing 2 horizontal parallel slits very thin and separated by a distance of 0.2 mm. We observe an interferance over a screen at 1.00 meter away from the screen containing the horizontal...
  4. C

    How Do You Calculate the Wavelength in a Closed Pipe Resonance Problem?

    Homework Statement -a pipe closed at one end resonates with a turning fork at a length of 25cm. The next resonant length is 75cm. The air temperature is 11.6C. What is the wavelength of the sound produced by the turning fork. Homework Equations 1st harmonic: lambda = 4 * L 3rd...
  5. GRB 080319B

    Photosynthesis Chlorophyll wavelength absorption

    Why do the chlorophyll in land plants absorb primarily in the blue and red wavelengths, http://en.wikipedia.org/wiki/File:Solar_Spectrum.png" ? Isn't more energy available in 500nm green light vs 700nm red light? E =\frac{hc}{\lambda}
  6. U

    How Medium & Temperature Affect Sound Waves: Frequency, Wavelength & Speed

    Homework Statement (1) A sound wave is traveling through air medium, if the medium is replaced by water, how that will affect the wavelength, frequency and speed of the wave ? (2) If the temperature of the air changed, how that will affect the wavelength, frequency and speed of the wave ...
  7. H

    What happens to wavelength and frequency when a wave changes velocity

    When an EM wave goes into say a denser medium and its velocity is decreased how does its wavelength and frequency change? I read that the frequency remains constant but the wavelength changes. Is this true? If so does that mean the wave gets compressed when it enters a denser medium. Does the...
  8. J

    What Wavelength Does a 100mW Laser Deliver 3.5x10^17 Photons in One Second?

    Homework Statement At what wavelength does a 100mW laser deliver 3.5 x 1017 photons in one second? h (plancks) = 6.626x 10^-34 c = 3 x 10^8 Homework Equations E = hf ==> E = hc / n (wavelength) ==> n = hc / E Power = Energy / Time The Attempt at a Solution Energy = Power *...
  9. K

    If you know the wavelength of light emitted by a laser how can you know

    Homework Statement How can you know "the difference between the two lasing energy levels?" Homework Equations n(lambda) = 2(pi)r E = hf mvr = n(h-bar) The Attempt at a Solution no clue
  10. L

    Wavelength of a laser exciting H atom from n =2 to n = 5

    1. A monochromatic laser is exciting hydrogen atoms from the n = 2 state to the n = 5 state. What is the wavelength of the laser? 2. frequency = f = delta E / h lambda = c/f 3. First, is the following approach valid: I find delta E by computing E5 - E2, where En = n2h2/8mL2...
  11. D

    The wavelength of the virtual photons of the Coulomb force

    Is there a way to calculate the wavelength, frequency or energy (per photon) of the virtual photons that charges exchange to account for the Coulomb force? This is assuming that it's always the same wavelength, of course.
  12. L

    Wavelength, frequency, and E field amplitude from magnetic field equation

    1. The magnetic field of an electromagnetic wave in a vacuum is B_z= ( 3.0 uT )*sin(( 1.00*107)x - omega*t) , where x is in m and t is in s. What is the wavelength and frequency of this magnetic wave? What is the amplitude of the E field? 2. wavelength = 2pi/k frequency = f = 1/T =...
  13. A

    Calculating the Fringe Width without the value of its Wavelength

    Homework Statement Young's fringes, produced by monochromatic laser light passing through slits 0.60mm apart, are viewed on a screen. The distance accrose 20 fringe spacings on the screen is 58mm. When the screen is moved 0.80m away from the slits, the distance across 20 fringe spacings...
  14. A

    How do you calculate finge width without the wavelength ?

    Homework Statement Young's fringes, produced by monochromatic laser light passing through slits 0.60mm apart, are viewed on a screen. The distance accrose 20 fringe spacings on the screen is 58mm. When the screen is moved 0.80m away from the slits, the distance across 20 fringe spacings...
  15. G

    Double Slits - Measuring Wavelength from the number of bright fringes

    Homework Statement A double-slit interference pattern is observed on a screen 1.0m behind two slits placed on 0.3mm apart. Ten bright fringes span a distance of 1.65cm. What is the wavelength of the light? Homework Equations Since we're looking at bright fringes: (m+1/2)\lambda =...
  16. S

    Wavelength of Proton: Kinetic Energy = Internal Energy

    How can I get the wavelength of a single proton if its kinetic energy is equal to its internal energy?
  17. D

    Excited hydrogen atom and wavelength

    i have been working on this question for quite a while. no help on google, or my textbook at all. A hydrogen atom in its ground state is excited to the n=5 level. It then makes a transition directly to the n=2 level before returning to the ground state. A) What are the wavelengths of the...
  18. L

    Quick question on calculating wavelength.

    Homework Statement Light strikes a sodium surface, causing photoelectric emission. The stopping potential for the ejected electrons is 4.6 V, and the work function of sodium is 2.2 eV. What is the wavelength of the incident light?Homework Equations The Attempt at a Solution Problem solved...
  19. P

    De Broglie wavelength of a neutron

    Homework Statement What is the de Broglie wavelength of a neutron whose kinetic energy is equal to the average kinetic energy of a gas of neutrons at temperature T = 17 K? Homework Equations lambda = h/p = h/mv. The Attempt at a Solution Well first I tried taking the h =...
  20. J

    Wavelength of sound waves and speed of sound in air column

    [b]1. You perform an experiment with a long column of air and a tuning fork. The column of air is defined by a very long vertical plastic tube with a circular cross section; the upper end of the tube is open to the outside air and the lower end of the tube is filled with water. The column of air...
  21. K

    Why does sodium light have two distinct wavelengths?

    why sodium has two lines D1 and D2 ?
  22. B

    Find the wavelength in the lab of grating spectrometer?

    I did a lab today using this stuff. I need to learn how to find the wavelength of the 1st order of an unknown filament. My data is 600 lines/mm grating Purple line 15 degrees 30 minutes, 15.5 degrees using the equation of d sin (angle) = m (lambda) im supposed to get something like...
  23. K

    Find wavelength in double slit experiment

    Homework Statement Two narrow slits are 0.4 mm apart. The dark fringe of order 5 is 1.2 degrees from the central bright fringe. What is the wavelength of the light in nm? Homework Equations dsin(theta) = (m +1/2)lambda where d = distance between silts m=order lambda = wavelength...
  24. W

    Decomposition of the wave-vector in terms of wavelength

    Im attempting a problem in relativistic optics that's asking me to write k_x, k_y and k_z in terms of lambda, c, and theta (theta being the angle between a source and an observer, at rest relative to each other). Lamda is the wavelength in this reference frame. I started off using trigonometry...
  25. C

    Spacing between slits in a diffraction grating w/o known wavelength

    Homework Statement I have an issue for a question I have. The problem is that I need to find the distance between the slits of a diffraction grating. Normally this would be pretty simple, but I'm not given the wavelength of the light source we're supposed to use to find it out. Homework...
  26. P

    What is Earth's de Broglie Wavelength and Quantum Number?

    Homework Statement Earth has the mass 6 · 10^24 kg and the orbit radius r = 1.5 · 10^11 m. (a) Compute its de Broglie wavelength. (b) Apply de Broglie quantization condition as in the case of the Hydrogen atom and compute the quantum number n for the orbit of Earth. (c) What is the...
  27. F

    Range of wavelength from white light through a diffraction grating

    Homework Statement A narrow beam of collimated white light falls at normal incidence upon a transmission grating with 3150 lines per cm. A spectrum is formed by the grating on a screen 30 cm away. If a 1 cm square hole is cut in the screen its inner edge being 5 cm from the zeroth order...
  28. O

    De Broglie wavelength of particle of diameter X

    Homework Statement In an electrom microscope we wish to study paprticles of diameter about 0.10 µm (about 1000 times the size of a single atom). What should be the de Broglie wavelength of the electrons? Through what voltage should the electrons be accelerated to have that de Broglie...
  29. T

    Wavelength of the wave which is produced at the wire

    Homework Statement The diagram attached shows a metal wire stretched between two supports P and T which are 4x apart where PQ=QR=RS=ST=x . Three small pieces of paper are placed at positions Q , R and S . When the wire is vibrated at a certain frequency , the small piece of paper at R...
  30. Q

    Why does long wavelength infrared not penetrate glass?

    Why does long wavelength infrared not penetrate glass?
  31. L

    What is the wavelength of the sound waves?

    Homework Statement a stationary sound wave has a series of nodes. The distance between the first and the sixth node is 30.0 cm. What is the wavelength of the sound waves? Homework Equations The Attempt at a Solution well no idea about it but in my attempt to solve it, i tried...
  32. G

    Quantum efficiency as a function of wavelength

    I'm trying to reproduce the plot in the attached figure. I know the band-gap energies, so I was hoping there was some simple way I could get the quantum efficiency as a function of wavelength. I read on wiki that Energy(eV) = 1240/wavelength(nm), so I mechanically plugged those in, and got...
  33. D

    What are the equations for wavelength and frequency in wave generation?

    Homework Statement I have a revision booklet page for homework, however my mind has went totally blank as to how to work out these equations. One question is "Jean is generating a wave by moving one end of the rope up and down 2 times every second (as shown in the diagram). Jean is 3m away...
  34. B

    How do you find wavelength if your given only the speed?

    How do you find wavelength if your given only the speed?
  35. O

    De Broglie wavelength of an electron

    Homework Statement Find the de Broglie wavelength of an 8 MeV proton. Homework Equations y = h/p where y is the wavelength p = mv K = Eo/sqrt(1-v^2/c^2) where Eo is the rest mass and K is the kinetic energy The Attempt at a Solution I make the assumption that "an 8 MeV proton"...
  36. O

    Finding the Compton wavelength of the electron

    Homework Statement h/(mc) = ? where m is the mass of an electron Homework Equations The Attempt at a Solution h = 4.136*10^-15 eV*s m = 0.511 MeV/c^2 c = 299792458 m/s So m*c (as long as I remember to multiply by 10^6) gives units of eV/c So h/(mc) gives units of s*c Using...
  37. B

    Does Wavelength Times Frequency Determine Speed of Light?

    equals speed? I only ask as I couldn't find a solid answer online.
  38. U

    Frequency, Time, Wavelength = Doppler Effect

    Homework Statement A small homemade firework goes off 3 meters about the surface of the water where a person is diving. The diver is 10 meters below the surface of the water. (a). How much time passes from the instant the firework goes off until the diver sees it? (b). How much time...
  39. A

    Swimming in short wavelength waves and high wavelength waves

    Hi all. Just wondering. Any difference - from the viewpoint of a swimmer - when one swims in water waves of short wavelength as compared to large wavelength? I read about this somewhere before in a newspaper article. The difference will be apparent when the length of the swimmer's body is...
  40. Y

    Emissivity as a function of wavelength

    Homework Statement Hello, I'm a little confused. I did an experiment today with a Leslie Cube. One of the faces was a black paint, and another a white paint. I know that white reflects well and has a low emissivity, at least in the visual wavelengths. In the Leslie's cube, was hot water, so...
  41. H

    Chromatic Dispersion, and Variability of Refractive Index on Wavelength

    Hi I'm trying to sort this concept out in my head and have reached a stumbling block! 1. ok so light travels through medium a and transmits through medium b and refracts. The angle or refraction is given by snell's law, and quantified by the refractive index of materials a and b. 2. But I...
  42. L

    Determing wavelength of sound wave from steel string

    Homework Statement A 120 cm-long steel string with a linear density of 1.2 g/m is under 100 N tension. It is plucked and vibrates at its fundamental frequency. What is the wavelength of the sound wave that reaches your ear in a 20 \circC room? Homework Equations Fundamental...
  43. S

    Exploring EM Wave Transmissions: Experiment & Wavelength

    Homework Statement a) A microwave transmitter T and receiver R are placed side by side facing two sheets of material M (aluminium) and N (hardboard). A very small signal is registered by R; what can you deduce about the experimental set up? b) When M is moved towards N a series of maxia and...
  44. U

    What is the wavelength of the helium-neon laser beam in the liquid?

    Homework Statement A helium-neon laser beam has a wavelength in air of 633nm. It takes 1.38 ns for the light to travel through 30cm of an unknown liquid. What is the wavelength of the laser beam in the liquid? (IN NM) Homework Equations v=wavelength*frequency v= d/t The Attempt...
  45. N

    Understanding the Wavelength of Photons

    What is photon wavelength?! What is photon wavelength exactly? I know that the energy of a photon is E = hc/lambda, where frequency = c/lambda and lambda is the wavelength. So, what determines the wavelength of a photon? Is it the distance an electron falls from the conduction band back down...
  46. F

    Atmospheric chemistry - how to find a wavelength

    Recently, it has been found that Cl2 can be released to the atmosphere in the marine boundary layer through mechanisms that oxidize chloride (Cl-) in sea salt aerosol. The Cl2 is unreactive at night and can build up to significant levels. Upon sunrise, Cl2 will photolyze, releasing very reactive...
  47. B

    Calculating Wavelength: Finding the Formula with 10cm Between Phases

    If I am given the measurement of 10cm between phases what is the wavelength? I couldn't find the formula for it in my book :S help?
  48. A

    Solving the 411nm Wavelength Emission from Hydrogen

    Homework Statement Light of wavelength 411 nm is emitted from a hydrogen discharge. What transition produces this emission? a. k = 5 to n =1 b. k = 4.5 to n = 2 c. k = 2 to n = 6 d. k = 2 to n = 3 e. k = 6 to n = 2 Homework Equations R = (1/n^2 - 1/k^2) The Attempt...
  49. T

    Why is the bending of waves related to wavelength?

    Why is the "bending" of waves related to wavelength? Hi! As stated in the title, my question concerns the "bending" of waves. (I'm quite sure that "bending" is not the proper term, so if you know the correct one, please tell me.) Let's say that we investigate waves in a ripple tank. We create...
  50. S

    Understanding wavelength and frequency.

    "when light enters from one medium to other its frequency remains same whereas wavelength changes." i'm not able to understand this relation as frequency has a inverse relation to wavelength please help me to understand it thoroughly.
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