What is Single slit: Definition and 156 Discussions

Diffraction refers to various phenomena that occur when a wave encounters an obstacle or opening. It is defined as the bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. The diffracting object or aperture effectively becomes a secondary source of the propagating wave. Italian scientist Francesco Maria Grimaldi coined the word diffraction and was the first to record accurate observations of the phenomenon in 1660.

In classical physics, the diffraction phenomenon is described by the Huygens–Fresnel principle that treats each point in a propagating wavefront as a collection of individual spherical wavelets. The characteristic bending pattern is most pronounced when a wave from a coherent source (such as a laser) encounters a slit/aperture that is comparable in size to its wavelength, as shown in the inserted image. This is due to the addition, or interference, of different points on the wavefront (or, equivalently, each wavelet) that travel by paths of different lengths to the registering surface. However, if there are multiple, closely spaced openings, a complex pattern of varying intensity can result.
These effects also occur when a light wave travels through a medium with a varying refractive index, or when a sound wave travels through a medium with varying acoustic impedance – all waves diffract, including gravitational waves, water waves, and other electromagnetic waves such as X-rays and radio waves. Furthermore, quantum mechanics also demonstrates that matter possesses wave-like properties, and hence, undergoes diffraction (which is measurable at subatomic to molecular levels).

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  1. S

    Single slit diffraction problem

    I've read that if you want light to diffract through a single slit, the slit opening must be equal too or less than the wavelength of the light. So for example, light of wavelength 600nm would diffract through a slit with width 600nm or less. Is this true? Or am I missing something. Since when I...
  2. applestrudle

    Double and single slit experiments - parallel light beams?

    Do we presume the light beams to be parallel even though they meet at one place? like the image here http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/sinslit.html
  3. M

    Single slit double slit and diffraction grating

    Homework Statement 1. From conservation of energy point of view if single and double slits, and diffraction grating had slits of same width, how should their overall light intestines compare 2. under what conditions can we consider double-slits intensities as approximately constant...
  4. J

    Bright Bands in Single Slit Diffraction

    Homework Statement A single slit forms a diffraction pattern with monochromatic light. The 4th minimum of the pattern occurs at an angle of 35 degrees from the central maximum. How many bright bands are on each side of the central maximum?Homework Equations Number of minimum brightness bands =...
  5. P

    Single Slit Problems: Calculate Width of Central Maximum

    Homework Statement A 0.42 -mm-diameter hole is illuminated by light of wavelength 510nm. What is the width (in mm) of the central maximum on a screen 1.8m behind the slit? Homework Equations f=λx/s The Attempt at a Solution I tried two answers, 4.4mm and 2.2mm and they are both...
  6. M

    How Is Wavelength Calculated in Single Slit Diffraction?

    Homework Statement What is the wavelength of the light whose first diffraction max (not counting the central max) falls at 15°,thus coinciding with the first min for red light?Width of slit=2510 nm." It is an example problem from Halliday Resnik Krane..In which the they use the principle...
  7. Q

    Single slit width change, how would fringes differ?

    just to be clear, this is single slit diffraction of light if the slit width is made narrower, this would lead to more diffraction, so the fringe width would be wider, yeah? but I'm a bit confused, because is this basically the same as saying the fringe separation would be wider?
  8. C

    Single Slit Diffraction question

    Homework Statement I'm having difficulty understanding why this equation makes sense for the following m values. Homework Equations The following is stated in my textbook. For dark fringes, sinθ = (mλ)/a where λ is the wavelength of light in nanometers and a is the width of the single...
  9. T

    Photons Moving Through a Single Slit (Uncertainty)

    Homework Statement The diagram is attached. Photons are being beamed with momentum \rho_{0} and mass m at a slit of width A Estimate the uncertainty \Delta p_{y} emerging from A Sketch spot size at B as a function of slit width using the uncertainty principle Determine minimum spot size...
  10. U

    Width of single slit diffraction

    Homework Statement Homework Equations The Attempt at a Solution Part(a) Diffraction is the bending of light about an aperture. To be able to resolve two distinct images, the minimum angle must satisfy the rayleigh criterion. Any angle smaller will hence affect the quality of...
  11. O

    What will happen for single slit diffraction if?

    If the width of the single slit is much smaller than the wavelength of a monochromatic light, until there is only one point on the wavefront can pass through it? Thank you
  12. M

    How Wide is the Central Bright Fringe in Single Slit Diffraction?

    Single slit diffraction Homework Statement Red light of wavelength 633nm from a helium-neon laser passes through a slit 0.390mm wide. The diffraction pattern is observed on a screen 3.00m away. Define the width of a bright fringe as the distance between the minima on either side. What is...
  13. C

    Young's double slit experiment vs single slit

    Why did Young specifically perform a double-slit experiment to demonstrate the wave nature of light, since light will diffract and interfere even through a single slit? Is there something special demonstrated by the double-slit experiment that's not demonstrated by a single-slit experiment...
  14. A

    Calculating Wavelength and Central Maximum Width Using Single Slit Equations

    Homework Statement A beam of light of unknown wavelength is incident on a screen with a single-slit. Observing the interference pattern on the projection screen that is 1.7 m away, the 4th minimum is 27 cm away from the central line. The width of the slit is 15 μm. a) What is the wavelength...
  15. G

    Understanding the Single Slit Diffraction Pattern

    I'm confused about the single slit diffraction pattern. Why are light and dark patterns? Where is the constructive and destructive interference occurring if there is just one wave?
  16. C

    Diffraction With A Single Slit And A Lens.

    Homework Statement Trying to find the number of diffraction maxima and the width of the whole pattern. \lambda = 500nm b = 2.8μm (Slit Width) f = 100mm r = 25mm L = 25mm (Slit to Lens) Homework Equations I have the worked out the irradiance formula as: I(\theta)=I_0...
  17. C

    Single electron single slit interference

    single electron diffraction through single slit Hi Guys Wondered if you could help me. Say a high energy electron (low wavelength?) is fired through an arrangement of atoms (single slit). How does a single electron hit a detector / screen according to a diffraction pattern? I understand...
  18. B

    Help With Simple Single Slit Diffraction Pattern?

    Homework Statement Plane light waves are incident on a single slit of width 2.45 cm. The second dark fringe is observed at 44.3° from the central axis. What is the wavelength of the light? Homework Equations θ=pλ/a... where theta is in radians, p =2 (second light minimum), and a = slit...
  19. J

    Diffraction from a single slit, with Lens

    Homework Statement Parallel rays of green mercury light with a wavelength of 546 nm pass through a slit covering a lens with a focal length of 60.0 cm. In the focal plane of the lens the distance from the central maximum to the first minimum is 10.2 mm. What is the width of the slit...
  20. T

    Determine resolution of use by modelling it as single slit

    Homework Statement Model the pupil of the eye using a single slit. If the eye is able to notice changes in intensity of 20% show that it can distinguish two objects separated by an angle of 0.00015 radians if =500nm and diameter=4mm. Homework Equations I=Iosin^2((π/λ)asinθ)/...
  21. S

    Single particle single slit interference - question about the experiment

    Came across the below experiment, on Wikipedia, but don't understand how it was performed... It was shown experimentally that: in a double-slit system where only one slit was open at any time, interference was nonetheless observed provided the path difference was such that the detected...
  22. D

    Polarization, Double Slit, Single Slit

    Homework Statement This is an old test question that I failed, but this material will resurface for the final so I just wanted a detailed description of what the full answer would've been. I'll include the rubric too so you'll know what I'm up against. Can you include explanations and...
  23. G

    Uncertainty principle and single slit experiment

    hi my concern is, that there is a huge amount of equations that are somehow related to the uncertainty principle and it is not straightforwardly obvious to me, when i have to use which of them. let me put it this way: as far as i see, there is this overall applicable equation that says ΔxΔp ≥...
  24. S

    Single slit single particle interference

    If we send one photon, at a time, through a single slit do we observe the interference pattern? Specially at the edges
  25. I

    How does the placement of a lens behind a slit affect the diffraction pattern?

    Homework Statement How does adding a lens behind a slit alter the diffraction pattern given you know it's focal length? Homework Equations I know currently that i'd look at equations such as: y_{n} = \frac{nD\lambda}{d} Destructive and so fourth But what about the lens, does that...
  26. J

    Physics - Single Slit Diffraction

    Hi Guys, my textbook mentioned that how the equation for the minima for single slit diffraction was derived: Consider a slit of width W with 2 light rays, one emitting from the edge, one emitting from the center. Their path difference is W/2 sin T . If the path difference is 1/2 lambda, then...
  27. perplexabot

    Finding WavelengthHow do I find the wavelength using single slit diffraction?

    Hi all. So let us say I shine a laser through a slit of width w, the distance to the screen is L, the distance from the center of the pattern formed to the first next bright fringe (next because the center is a bright fringe) is a. Using Fraunhofer diffraction. Given variables: a, w and L...
  28. T

    Single slit interfernce with large particels

    Why and how do large particles emit single slit interference, also why do electrons not. Also do single atoms display single slit interferance? How is this explained by the copanhagen interpretations as opposed to the bohm interpretation? How does bohm explain single slit collapse with...
  29. C

    Diffraction through a single slit

    This isn't a homework question per se, I'm just wondering about something in my textbook (Halliday & Resnick) that isn't clear to me: This figure shows intensity as a function of angle (0 degrees is the center) for three experiments that use single slits of different width. The one on the...
  30. P

    Single Slit Diffraction find central maximum

    Hi, I have tried tackling these question but I am simply absolutely lost... 1. A single slit of width 1.50 um is illuminated with light of wavelength 500.0 nm. Find the angular width of the central maximum. I have no attempt for number 1. 2. Microwaves of wavelength 2.8 cm fall on...
  31. G

    Intensity of single slit and double slit

    After looking at the graphs of single slit and double slit interference of intensity vs. angle, it seems that the intensity drops off very steeply with single slit interference but doesn't drop off at all with double slit interference patterns. Why is that?
  32. K

    Single slit diffraction pattern

    Homework Statement A single slit forms a diffraction pattern, with the first minimum at an angle of 40 from the central maximum. Monochromatic light of 410 nm wavelength is used. The same slit, illuminated by a different monochromatic light source, produces a diffraction pattern with the...
  33. E

    Single slit interference and Diffraction Grating

    Lets say I have a double slit interference experiment set up. Now if I cover one slit what CHANGES would be observed ? I know I would see fewer bright fringes and that the intensity of the bright fringes would fall. Is there anything else ?In a different scenario I have a diffraction grating...
  34. P

    Single slit diffraction problem

    Homework Statement A single slit 10-4m wide(a) is illuminated by plane waves from helium-neon laser ( l = 6.328*10-7m). If the observing screen is 10m(D) away, determine the width of the central maximum(y). Homework Equations sin(alpha)=(m+0.5)*l/a tan(aplha)~sin(alpha)=y/2*D...
  35. B

    Can the intensity of soundwaves be affected by the size of a gap?

    Ok so I was sitting out back one day listening to some music with some friends around. We had some music playing on a stereo inside the house and we were out the back with the glass door open about 10 cm's. I thought I noticed that some sounds with different frequencies seemed louder then...
  36. jegues

    How Do You Determine the Exact Phase Difference in Single Slit Diffraction?

    Homework Statement See figure attached. Homework Equations The Attempt at a Solution \Delta L = asin\theta = m \lambda If the waves are in phase, we would expect L to me a integer number of wavelengths, when they are out of phase, L should be an odd number of wavelengths, but...
  37. JJBladester

    Single Slit Diffraction light intensity

    Homework Statement This is the light intensity on a viewing screen behind a rectangular opening in a screen. Is the shape of the opening (1), (2), or (3)? Homework Equations w=(2λL)/a where w is the width of the central maximum, L is the distance to the viewing screen, and a is...
  38. jegues

    Double Laser Interference: Solving for Small Angles

    Homework Statement See figure attached for problem statement as well as my attempt Homework Equations The Attempt at a Solution I don't know where to go from here. Can someone help me get started?
  39. 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...
  40. 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...
  41. A

    Calculating Third Maximum in Single Slit Illuminated by He-Ne Laser

    Homework Statement A single slit is illuminated with a helium-neon laser whose wavelength is 633 nm. If the slit width is 2.2 x 10 e-5 m, calculate the position of the third maximum in degrees Homework Equations Sin Theta(m) = (m + 0.5) Lambda/w The Attempt at a Solution...
  42. G

    Why does laser on a hair/wire creat a single slit?

    I was wondering why laser on a hair makes the hair act like a single slit. I already know about Huygen's Principle behind it and all that. But what is it that can convince you that it actually is a SINGLE slit and not a double, other than just seeing it by measuring min. and using mλ = d * sinα...
  43. H

    Electron Single Slit Diffraction

    Homework Statement Electrons pass through a 10-6m wide slit with a speed of 1.5 x 106m/s. How wide is the electron diffraction pattern on a detector 1 m behind the slit. Homework Equations \lambda=h/mv (matter waves) asin\theta=m\lambda (path length difference for constructive...
  44. C

    How Does Light Interact with a Slit in Single Slit Diffraction?

    When light goes through a narrow single slit it diffracts. And you can explain this with the uncertainty principle or the wave-like nature of light. But if a photon can only be in one medium at a time then how does it know its going through a slit , How is it interacting with the edges of the...
  45. fluidistic

    Single slit, optics, special case

    I've thought about the case when the wavelength of the incident EM waves on a single slit is much greater than the width of the slit. When we have \lambda >> D. It could be the case of a radiowave incidating over a single slit whose width is day a nanometer large. According to Hecht, the...
  46. J

    Single Slit Diffraction and Monochromatic light

    Monochromatic light with a wavelength of 419 nm passes through a single slit and falls on a screen 88 cm away. If the distance of the first-order dark band is 0.29 cm from the center of the pattern, what is the width of the slit? My knowns are as follows: L= 88 cm (distance from slit to...
  47. S

    Single slit diffraction experiment

    I'm a novice at this quantum business and was just trying to understand the single slit diffraction experiment and when an electron's position is getting measured in particular. Given my understanding it looks like the electron's position gets measured twice. Once when it is just about to...
  48. L

    Single slit diffraction distance

    What happens to the distance between fringes as the width of the single slit become larger? Does the distance between fringes increases? What happens to the centre bright fringe? Does it become larger with an increasing single slit width? My hunch is: Increasing the width increases the size of...
  49. L

    Single slit diffraction - distance between 1st&2nd order dark fringes

    Homework Statement Monochromatic light with wavelength 580nm passes through a single slit 2.60um wide and 2.10m from a screen. Find the distance between the first- and second-order dark fringes on the screen. Homework Equations y=(n*lamda*L)/d The Attempt at a Solution...
  50. A

    Single Slit Diffraction Problem?

    Homework Statement Monochromatic light of wavelength 441 nm falls on a narrow slit. on a screen 2.16m away, the distance between the second minimum and the central maximum is 1.62 cm. a) calculate the angle of diffraction thetta of the second minimum. b) find the width of the slit? Rensick...
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