Wavelengths Definition and 231 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.

View More On Wikipedia.org
Recent contents Top users
  1. J

    Re: CMB Redshift Question (Visible Wavelengths)

    The earlier thread was closed for some reason. It prompted this question: Given the formula for CMB temperature Tobs = Tem/(1+z) (analogous to the formula for z) it seems the age of the universe at the emission of the CMB would have been about 12.5 Myr (if 13.75 Gyr presently), not 380,000...
  2. L

    Something that absorbs at longer wavelengths looks more red?

    So the colors we perceive are a result of photons of a certain wavelength being reflected back at us. So why in a recent experiment I did, did nanoparticles which had an absorption band that red shifted as the reaction proceeded, look more and more red from an initial yellow color? If the...
  3. Z

    How to estimate how many wavelengths wide a laser is?

    Homework Statement I've conducted two laser experiments. One with single slit, and one with a double slit. I've produced two graphs which look something like these...
  4. C

    Wavelengths / film / reflected light

    Homework Statement A film of MgF2 (n = 1.38) having thickness 1.44 x 10-5 cm is used to coat a camera lens. What are the three longest wavelengths that are intensified in the reflected light? (Enter your answers from smallest to largest.) Homework Equations λn = λ/n n = index of...
  5. O

    Wavelengths along a Smith Chart

    Hello, This may be something that is more mathematical than electrical, but I figured here was the best place. I am going through a worked example, and there is something I don't understand. The question is as follows Find the imput impedance and return loss (in dB) of the loaded line...
  6. P

    Index of refraction of different wavelengths

    Homework Statement Monochromatic light of variable wavelength is incident normally on a thin sheet of plastic film in air. The reflected light is a maximum only for 482.9 and 676.0 in the visible spectrum. What is the minimum thickness of the film ? Homework Equations 2nt=m*lambda...
  7. S

    Tension in a rope, wavelengths, etc. I

    Homework Statement A rope is stretched between two vertical supports. The points where it is attached (P and Q) are fixed. The linear density of the rope, u, is 0.6kg/m, and the speed of the transverse waves on the rope is 12 m/s. a. what is the tension in the rope? b. with what frequency...
  8. P

    Air vs Water Sound Wavelengths: Calculating at 10°C | Grade 11 Help ASAP

    Please solve showing all work asap thanks sooo much How many times more wavelengths occur in air than in water for an air temperature of 10 degrees Celsius if the speed of sound in water id 5220 km/hour and the frequency of sound is 500 Hz. Grade 11, thanks so much please ASAP
  9. P

    Calculation of a planet's mass via wavelengths

    I got to find an answer or a push to the right tracks on this question. Suppose a spacecraft is in a circular orbit about a distant planet. the spacecraft emits a continuous radio signal with a wavelength of 6m. The signal's wavelength varies between 5.99969m and 6.00031m; the period of...
  10. B

    Diffraction grating problem involving two wavelengths.

    Homework Statement A diffraction grating has 4,200 rulings/cm. On a screen 2.00 m from the grating, it is found that for a particular order m, the maximum corresponding to two closely spaced wavelengths of sodium (589.0 nm and 589.6 nm) are separated by 1.54 mm. Determine the value of m...
  11. P

    Doppler Effect (Proving equal wavelengths )

    Hi, I am doing doppler effect and this question wants me to prove that the wavelength perceived by the observer and that of the wave emitted is the same. I tried doing it but couldn't, so I checked out what they had as an answer: They said that the wavelength of the emitted wave is: v...
  12. B

    Wavelengths due to electric dipole transitions

    Homework Statement Having problems with this subject. Given hydrogenic carbon, with binding energies of 490 eV (1s) 857.50 eV (2p) 925.54 eV (3p) 949.36 eV (4p). Find wavelengths of all lines due to electric dipole transitions between the levels. State which you expect to be strongest...
  13. J

    I just noticed that we tend to call EM wavelengths shorter than

    I just noticed that we tend to call EM wavelengths shorter than visible light "rays" while we call we call those that are longer "waves". Why is that? Did we ever think that "rays" and "waves" were physically different?
  14. B

    Help with an equation about waves and wavelengths

    1. A standing wave is set up on a taut string. The string is vibrated at a frequency of 350 Hz. The string is 1 m long and a total of 6 antinodes are counted along its length. What is the wavelength of the standing wave? And what is the speed of the wave in the string? 2.I'm unsure of...
  15. W

    How far away is the rock face? (Wavelengths)

    1. A submarine sonar system sends a burst of sound with a frequency of 325 Hz. The sound waves bounces off an underwater rock face and returns to the submarine in 8.50s. if the wavelength of the sound wave is 4.71 m, how far away is the rock face? The answer is 6.51 x 10^3m. I keep trying...
  16. L

    Does anyone know what the smallest and longest wavelengths of light

    Does anyone know what the smallest and longest wavelengths of light are? As far as I am aware radio and gamma waves are the longest and shortest types respectively. But is there a limit to how long a radio wavelength could be?
  17. B

    Calculating Speed from Light Wavelengths

    Homework Statement I drive through a traffic light. When I was pulled over, I tell the police that the red light of wavelength 675 nm appear green to me, with a wavelength of 525 nm cause of doppler effect. How fast was I traveling? Homework Equations \Delta \lambda / \lambda = v/c v is the...
  18. Vorde

    Different Wavelengths of Light in Particle View

    I completely understand how different shades of light (red, blue, UV, Radio etc...) can be explained when light is viewed as a wave (different wavelengths etc..). However I am curious as to how different frequencies of light are possible when light is considered as photons instead of a wave...
  19. S

    Wavelengths of different colour of light

    Hey guys Today I've done an experiment and I found that when different color of light from the same light source (put of different color filter on the same light source) shine on a beaker of water, the temperature of the water will rise. And different light will rise the temp of water in...
  20. E

    Diffraction with two wavelengths?

    Homework Statement "White light contains wavelengths from 4.00 x 10^-7 metres to 7.00 x 10^-7 metres. This white light is directed on a diffraction grating ruled with 5.50x10^4 lines/metre. How wide is the first-order spectrum on a screen that is 1.25m away from the grating? Homework...
  21. L

    Radio wavelengths for carbon monoxide (how to find atomic number

    Homework Statement ...Consider a di ffuse gas cloud that contains carbon monoxide (CO) molecules... What are the radio wavelengths (in cm) and frequencies (in GHz = gigahertz = 109 Hz) corresponding to transitions between the ground state, the first excited state, and the second excited...
  22. L

    Multiple wavelengths of light through much larger single slit

    A text I am reading noted that as a multichromatic light source (consisting of many individual peaks) is passed through the my slit (order .25mm) the peaks will be spread over the neighboring wavelengths in a roughly Gaussian distribution. I am trying to understand why this is, and how I would...
  23. L

    Multiple wavelengths of light through much larger single slit

    A text I am reading noted that as a multichromatic light source (consisting of many individual peaks) is passed through the my slit (order .25mm) the peaks will be spread over the neighboring wavelengths in a roughly Gaussian distribution. I am trying to understand why this is, and how I would...
  24. K

    Doppler Effect: Wavelengths of Sound Waves

    Homework Statement I read that when a body approaches a stationary one which emits radar waves, the wavelength λ2 of the returned waves is longer than λ1, the wavelength of the emitted ones, but I get the opposite. I suppose this is true for sound waves also. See picture. The Attempt at a...
  25. 6

    Wavelengths of Light: Color Wheel & Measurements

    Been looking on the internet for a long time, trying to find wavelengths of light. The sites I've seen have the wavelengths of the basic colours (red, blue, green etc.). I'm looking for the wavelengths of intermediate colours, (pink, aquamarine, turquoise etc.). Is it possible to find a colour...
  26. N

    What Range of Frequencies Corresponds to 400-700nm Wavelengths?

    Homework Statement The human eye is sensitive to light of wavelengths from about 400 to 700nm. What range of frequencies does this range correspond to? Take the speed of light to be 3.00 x 10^8 m/s. Homework Equations f=v/lambda The Attempt at a Solution 3.00 x 10^8 / 400,000m =...
  27. L

    Why do different objects absorb and reflect different wavelengths of radiation?

    For example, humans emit primarily in the Infrared part of the spectrum, so then why is it that when visible light falls upon us, it is not converted to heat immediately?
  28. A

    Number of Wavelengths Emitted from Excited Atomic Hydrogen Level 4

    Homework Statement hi i came across this problem on an aqa physics a past question. How many different wavelengths of electromagnetic radiation can be emitted after atomic hydrogen is excited to level 4? Homework Equations The Attempt at a Solution i was looking at...
  29. R

    How many wavelengths are there now in one pulse?

    Homework Statement A certain type of laser emits light that has a frequency of 5.1* 10^14 Hz. The light, however, occurs as a series of short pulses, each lasting for a time of 2.6* 10^-11 s. (a) How many wavelengths are there in one pulse? (b) The light enters a pool of water. The frequency...
  30. H

    Range of wavelengths from a laser pulse?

    Homework Statement "A 1 fs pulse of laser light would be 0.3 um long. What is the range of wavelengths in a 0.3 um long pulse of (approximately) 600nm laser light?" Homework Equations (delta omega)(delta t) >= 1/2 c = (lambda)(frequency) The Attempt at a Solution I replaced (delta...
  31. L

    Wavelengths of a laser pulse and inductance in tuning of an FM radio

    Homework Statement Pulsed lasers used for science and medicine produce very brief bursts of electromagnetic energy. If the laser light wavelength is 532 nm, and the pulse lasts for 37 ps, (a) how many wavelengths are found within the laser pulse? (b) How brief would the pulse need to be to...
  32. L

    Deviation of wavelengths through barium crown pism

    Homework Statement The refractive index of an equilateral prism of dense barium crown glass varies with wavelength as given in the table wavelength (nm)...n 656.3...1.635 486.1...1.646 making use of Cauchy's dispersion formula determine the minimum angle of deviation for sodium light with...
  33. O

    Diffraction grating wavelengths question

    Hey guys this is the problem i need to solve: Light consisting of two wavelengths which differ by 160 nm passes through a diffraction grating with 2.50 x 105 lines per metre. In the diffracted light, the third order of one wavelength coincides with the fourth of the other. What are the two...
  34. G

    What Wavelengths of Light are Most Effective for Photosynthesis?

    What wavelengths of light can plants grow in? Which do they grow best in? How much does this differ from plant to plant? For example, could you grow a plant under monochromatic light? Infrared light? UV light?
  35. P

    What are the resonant wavelengths?

    Homework Statement Consider pipe of length L. The pipe is closed at one end and open at the other allowing a standing wave where a node exists at the closed end and a max exists at the open end. a) what are the resonant wavelengths? b) If L=5, what is the lowest frequency? Homework...
  36. D

    De Broglie wavelengths and electron diffraction

    I am interested to know why in any description of electron diffraction apparatus they seem to suggest that the electrons need accelerating up to 5kV (or at least several kV) to show the electron diffraction rings, this seems to give a de Broglie wavelength of around 1.2 x 10^-11m whereas the...
  37. A

    Wave & Wavelength: Exploring Questions & Answers

    Are waves only 'waves' if you try and represent them in 2D? If an object emits waves in all directions are the waves more like expanding spheres? If a wave/sphere hits us and the source is sufficiently far away (and strong?) do we 'experience' it as though being hit by a plane? or multiple...
  38. S

    Angular separation between two wavelengths

    1. using differentiation,find the angular separation in arc minutes in second order for two wavelengths 589.0 and 589.6 nanometers 2. d sin(\theta)=m (\lambda) 3. i try to use D=\delta\theta/\delta\lambda by differentating d sin(\theta)=m (\lambda) i got d/m sec(thetha).this...
  39. Z

    Stargazing Can Telescope Size Indicate Wavelength Range?

    I have been reading an article that refers to telescopes but I don’t really understand telescope sizes; http://www.eso.org/public/news/eso0226/ For instance take the 3.5-m New Technology Telescope. I assume that the 3.5m refers to the diameter of the parabolic mirror. Does the 3.5m...
  40. L

    What Do Wave Crests in Electromagnetic Radiation Represent?

    On Wikipedia and in the textbooks, it is very general and it does not explain so, curious, for the different wavelengths of radiation, (or light) what do the wave crests actually correspond to? Do they correspond to the electron making a complete orbit around the nucleus, or to something...
  41. B

    Separation of two wavelengths in a diffraction grating.

    Homework Statement Light with two wavelengths (510.0 nm and 525.6 nm) is spread by a diffraction grating. On a screen 4 meters behind the grating we observe that the diffrence between the two second order maximum is 1 cm. What is the grating constant (d) ?Homework Equations I think i only need...
  42. S

    Infared WAvelengths in transition through energy levels

    Homework Statement How many transitions involving the hydrogen energy levels shown correspond to photons of infrared light? The infrared range is less than 1.8 eV Homework Equations Paschen Lines = Infared wavelengths The Attempt at a Solution I thought that since Paschen lines =...
  43. J

    Wavelengths introduction please

    Homework Statement So, I was wondering how I can correlate frequency, amplitude, wavelength, period, and time with each other. I'm trying to solve this problem. A 4.5 Hz wave with an amplitude of 12 cm and a wavelength of 27 cm travels along a stretched horizontal string. a) how far does a...
  44. N

    Why do black bodies emit light at all wavelengths when heated?

    Why do "black bodies" emit light at all wavelengths when heated? Light emitted from an object is made of photons that are emitted when electrons drop into lower energy states. And there are only certain energy states in an atom that electrons can occupy, so only certain wavelengths (aka...
  45. E

    Find how many wavelengths of a wave are in a section of wire

    1. A string with linear density 2.0 g/m is strecthed along the positive x-axis with tension 20N. One end of the string, at x=0m, is tied to a hook that oscillates up and down with a frequency of 100 Hz and a max displacement of 1.0mm. AT t=0s, the hook is at its lowest point. a) What are the...
  46. B

    Wavelengths in a ripple tank experiment

    In a ripple tank experiment, students generate water waves at a speed of 4.0 cm/s and a wavelength of 0.5 cm. If the waves are refracted into shallower water where their speed decreases to 3.0 cm/s, what is their new wavelength? What would the formula be for this question?
  47. M

    Calculating Resonance Wavelengths

    Homework Statement Hello all, I am supposed to calculate the resonance wavelength by using the average difference between my measurements of each 1/2 wavelength. My data: Frequency = 2501 Hz (s^-1) Avg. difference of each 1/2 wavelength = 4.2625 cm Length of tube used to perform...
  48. P

    Electromagnetic Spectrum Wavelengths

    The question I have is a bit difficult to express. The foundation of my question. Within the electromagnetic spectrum there is the visible spectrum. Broken down that has our individual colors that we see. Do all portions of the electromagnetic spectrum have special properties such as...
  49. E

    Wavelengths increasing with space?

    please could somebody please explain how and why the wavelengths of photons increase with the expansion of space? thanks. i thought i understood the whole expansion acording to the Hubble law and the scale factor thing, and the surface of last scattering, and the redshift, but this...
  50. morrobay

    Y displacements in sine wave at (x) and (x + 2 wavelengths)

    Homework Statement A sine wave in + x direction with max amplitude of 1 wavelength= 2.85 m wavenumber, k = 6.28/2.85 m = 2.2 rad/m w=8rad/m frequency=1.27 cyc/sec vel.= 3.63 m/sec at x = 20m t= 5.5 sec at x + 2 wavelengths x= 25.7m t=7.07 sec by definition the y displacement is the...
Back
Top