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. A

    B Explanation for bright fringes in Single Slit Diffraction

    In Young's Double Slit Experiment, we were shown the complete derivation for location of fringes, width of fringes etc. on interference by two point sources of light and all was well. In Single Slit Diffraction we were just asked to remember the formulae as they were with little explanation. I...
  2. jaumzaum

    I Amplitude of the maximums in single slit diffraction

    Hello! I was trying to calculate the amplitude of the secondary maximums in the single slit diffraction. When I use the formula: $$ I = I_0 (\frac {sin(\Delta \phi /2)} {\Delta \phi /2})^2 $$ If I take ## x = \Delta \phi /2 ## and derivate I get that the maximum occurs when: $$ x = tan(x) $$...
  3. belbin09

    Single Slit Interference Pattern: Increased Distance

    ATTEMPT AT SOLUTION The effect on the pattern when the screen is moved further away is the bright fringes would become wider, the light intensity of the bright fringes would decrease, and the bright fringes will appear closer together. REASONING I answered this question based on how light...
  4. amjad-sh

    I Calculating Intensity in Single Slit Diffraction Experiments

    In a single slit diffraction experiment, when we want to calculate the intensity of light on a screen located very far away from the slit, usually Huygens' principle is adopted as a model to perform the calculations. It is assumed that the width of the slit consists of an infinite number of...
  5. S

    Derivation of single slit diffraction formula

    I want to ask several questions regarding to the text: 1) Why do we find the minima of the diffraction? Why not the maxima?2) "Figure 25.32b shows two rays that represent the propagation of two wavelets: one from the top edge of the slit and one from exactly halfway down" Why do we take point...
  6. O

    Angular Width Question in Single Slit Diffraction

    i feel like subbing the numbers into the equation isn't enough because of the second minima and maxima thing? not sure what to do... would appreciate any help.
  7. hairey94

    Diffraction of Light (Single Slit)

    My initial guess... Third dark fringe is 2nd order dark fringe and second bright fringe is 1st order bright fringe. Is this the correct guess?
  8. L

    How can a single slit diffraction create an interference pattern?

    I explained that Huygens principle states that each point on the wave front act as a point source which produces spherical waves which produce the interference pattern. Now his question is that where are these points and wouldn't there be infinite number of points on each wave front creating...
  9. Z

    I Double slit mystery in relation to holography and the single slit?

    What part of double slit mystery remains considering single slit can produce interference pattern as well? Does holography not fully explain those patterns behind any number of slits as a sort of "encoded image" of the slit(s)? Does the word "focus" have any meaning in these kinds of experiments?
  10. C

    Slit Width & Single Slit Diffraction

    Homework Statement Consider ultrasound with a frequency of 40 kHz. (a) What is the wavelength and period of a 40 kHz sound wave? (b) The slit width required to give the first order diffraction minimum at thirty degrees. (c) Calculate the angles at which the first three minimums should be...
  11. R

    Understanding Diffraction at a Single Slit: Notes and Resources

    [Mentors' note: This thread has been edited to change the level tag from 'A' to 'I'] Hello guys, I want the deduction part of- diffraction at single slit: Plz sent me the notes of this.
  12. G

    Uncertainty for a particle diffracted through a single slit

    Homework Statement A horizontal beam of laser light of wavelength 486 nm passes through a narrow slit that has width 0.0590 mm . The intensity of the light is measured on a vertical screen that is 2.90 m from the slit. What is the minimum uncertainty in the vertical component of the momentum...
  13. C

    More slits, farther maxima of interference patterns, why?

    When observing interference patterns, one will notice that the maxima from a double slit are more intense and farther apart than the maxima of a single slit. Likewise, the maxima from a diffraction grating are more intense and farther apart than maxima of a double slit. Why is this? I...
  14. D

    Single Slit Diffraction and Interference Maxima

    In a single slit experiment if the condition of interference maxima be asinΘ=nλ where n=1,2,3,4... and the condition of diffraction minima is also the same Will it not cause any effect on the intensity of the interference maxima as both are at a same distance from the central maximum on the...
  15. A

    Single Slit and Diffraction Grating Formulas

    Hi everyone. I am having some difficulty understanding the formulas of single slit diffraction and diffraction gratings. This is partly because the formulas that I have been given in class do not reflect what I have found online entirely. As we know, the formula for single slit destructive...
  16. L

    Single-slit Diffraction Problem

    Homework Statement A spy camera is said to be able to read the numbers on a car’s license plate. If the numbers on the plate are 5.0 cm apart, and the spy satellite is at an altitude of 160 km, what must be the diameter of the camera’s aperture? (Assume light with a wavelength of 550 nm.)...
  17. D

    Single Slit Fraunhofer Diffraction

    Just to clarify, this isn't homework. I took an Optics course a few years ago, but in the time between then and now, I've lost all my notes. Suppose we have an infinitely tall slit of width a and a parallel screen a distance r_0 away. Let the x axis be parallel to the width of the slit, with...
  18. H

    Single slit with minimum uncertainty

    Homework Statement A horizontal beam of laser light of wavelength 474 nm passes through a narrow slit that has width 5.80×10−2 mm . The intensity of the light is measured on a vertical screen that is 2.40 m from the slit. Use the result of part A to estimate the width of the central diffraction...
  19. L

    A laser emitting light with a wavelength of 560 nm (Single slit).

    Homework Statement Homework EquationsThe Attempt at a Solution a) see attached. b)[/B] i) Decreasing the width of the slit will cause less interference fringes to be seen, increases the distance amongst fringes and the fringes become wider. ii) If the screen was moved further away, fewer...
  20. Titan97

    Uncertainty in single slit diffraction

    Homework Statement An electron is moving in a parallel beam along the x-direction with momentum, p=mv. It encounters a slit of width w. Assuming that the electron gets diffracted somewhere within the central maximum of small angular magnitude Δθ, estimate the uncertainty Δp in its momentum...
  21. E

    Hair/wire laser diffraction interference pattern

    Hair/wire laser diffraction interference pattern - does it follow single-slit or double-slit? for single-slit interference, the equation nλ = d (y/D), (d is the width of the single-slit, y is the distance between central BRIGHT fringe to the nth DARK fringe, D is the distance from slit to...
  22. W

    Single Slit Diffraction Intensity

    Homework Statement A narrow slit is illuminated by a collimated 633-nm laser beam as shown in the figure below. This produces a diffraction pattern on a screen, which is 6 m away from the slit as shown in the figure below. The distance between the centres of the first minima outside the central...
  23. L

    Uncertainty -- particle through single slit

    Homework Statement Some particles pass through a single slit of width W = 0.17 mm. After the particles pass through the slit they spread out over a range of angles. The de Broglie wavelength of each particle is λ = 561 nm. Use the Heisenberg uncertainty principle to determine the minimum range...
  24. NatFex

    Distance between fringes in an interference pattern?

    For the sake of simplicity let's suppose I'm talking about the diffraction of light through one slit. Are the distances between any two consecutive fringes (apart from the central maximum) exactly equal? Assuming the wavelength, slit width, and distance between slit and screen do not change...
  25. D

    I Laser diffraction through single slit

    Will a laser diffract through a single slit if the laser beam width is smaller than the slit? Such that the laser beam can pass though without touching the sides.
  26. T

    Questions of single slit diffraction

    Homework Statement I have a question on a practice midterm my professor sent out. I would ideally ask him, but I won't see him until itake my midterm. Instead I am attaching the question and solutions at attachments. THe question of interest is in the attachment "physics question" and the...
  27. I

    Interference - Single slit diffraction

    < Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > Hi guys, I have a question here which I'm struggling to do and perhaps you could help ; Monochromatic electromagnetic radiation with wavelength λ from a distant source passes through a slit. The...
  28. C

    Can Fraunhofer Single Slit formula be used in this case?

    A question like : A very thin layer of oil is on the surface of a puddle of water. If the layer of oil is 400 nm thick, what frequency of light in the visible part of the spectrum will most strongly be reflected? Given the index of refraction of oil is 1.4. Can we think of the layer as a single...
  29. Ramesh Manian

    Diffraction in a single slit setting

    In a single slit diffraction setting, if the width of a slit is not much wider than the diameter of a particle such as a photon or an electron, would we still see diffraction bands? If so, is the number of bands / spots you see on the screen across is finite? I am a little confused by the...
  30. Summer95

    What does "minimum range of uncertainty" mean in QM?

    Homework Statement [/B] The problem on where the photon will hit a screen, after passing through a single horizontal slit. I know the wavelength, slit width, magnitude of momentum of incoming photon (calculated), and distance between screen and slit. Homework Equations I just don't...
  31. A

    Single slit diffraction confusion

    I've found this a very confusing thing:when we locate the second dark fringes above and below the central maxima,we divide the slit into four parts and claim that pairs of waves interfere destructively as the path difference would be wavelength/2.But what if we just divided it into two parts and...
  32. lulzury

    Small Angle Approximation in Single Slit Interference

    Homework Statement A monochromatic light source is used with a double slit to create an interference pattern on a screen that is 2.00 meters away. If the 2nd bright spot is observed 8.73 mm above the central maximum, can the small angle approximation be used? Show and/or explain your reasoning...
  33. S

    Double slit over time, single slit in moment

    What happen if you do the following version of the double slit experiment: In first sequence the right slit is open and the left is closed, and a number of electrons are sent through. Then the right slit is closed and the left is opened, and a new sequece of electrons are fired. After completing...
  34. J

    Single Slit Experiment: Details & Equations

    Hello! I am looking for resources to give me details of the single slit experiment. I want to code a simulation of the experiment, but most information i find is too simple or missing details. I need equations for the two angles of the particle (angle with respect to x direction and angle with...
  35. D

    Can a Diffraction Pattern be Solved Without Complete Information?

    Homework Statement A single slit illuminated by light of wavelength λ = 610 nm produces a diffraction pattern with its first minimum at 3.5 mm from the central maximum. (a) Find the slit width, and (b) For the same slit, what wavelength of light would produce a first minimum at θ = 4.0...
  36. A

    Nodal lines and single slit experiment

    Homework Statement The diagram above shows a single slit with lines marking the direction to a point P in the diffraction pattern. Two wavelets at x and y pass through the edges of the slit as shown. The possible value for path difference, py-px, that places P at the second nodal line next to...
  37. julianwitkowski

    Single Slit / Wavelength / Central Maximum

    Homework Statement A laser emitting light with a wavelength of 560 nm is directed at a single slit, producing an interference pattern on a screen that is 3.0 m away. The central maximum is 5.0 cm wide. Determine the width of the slit. I have two ideas of the answer but I'm not sure which is...
  38. O

    Can interference occur without the use of single slit?

    I wonder can a sustained interference pattern be obtained in Young double slit experiment if we do not use single slit between source of light and the double slits when one has a monochromatic source in the experiment. Regards
  39. Q

    Single Slit Problems: 750nm Light & 2.0um Width

    Homework Statement At what angle will 750nm light produce a second minimum if the single-slit width is 2.0um Homework Equations Sin(theta)=n(lambda)/w The Attempt at a Solution This is what I got so far (theta)=sin-1(3x10^-6/2x10^-6) I don't understand why I keep getting error on my...
  40. D

    How Does Changing Wavelength Affect the Central Peak in Single-Slit Diffraction?

    In my physics book, one of the basic quick quizzes checkpoints asks what happens to the central peak in a diffraction envelope when you decrease the wavelength of light (from 650 nm to 450 nm, for reference). My understanding is that the width of the peak would decrease, while the number of...
  41. D

    Intensity of single slit and double slit problem

    For a double slit experiemnt, the bright fringe has intensity of I, when one of the slit is covered, the intensity is 0.25I. In my opinion, the slit now become single slit, so it has area of half of the initial area, but we know that power is the product of intensity x area, by keeping the...
  42. J

    How wide is a single slit that gives its first minimum at 90°?

    Homework Statement How wide is a single slit that gives its first minimum at 90°? Homework Equations øp=p(λ/a) The Attempt at a Solution Not quite sure what the answer is looking for but I'd guess I would need to solve for "a." So... 90°=(λ/a) Is there any more...
  43. A

    Single slit diffraction pattern in 2D

    Hi all, I was looking at previous exams and I saw a question with single slit diffraction. Please look at picture. So, this made me think: "Wow, I never thought single slit diffraction could be applied in 2D with one pattern horizontal and the other vertical." Then, I thought why is...
  44. Greg Bernhardt

    Single Slit Diffraction: Definition & Equations

    Definition/Summary This entry describes diffraction of a wave when it passes through a single narrow slit. Equations The far-field (Fraunhofer) diffraction pattern has a power per area (irradiance) at an angle \theta from a single slit of width d, for wavelength \lambda and wavenumber k\ =\...
  45. X

    Understanding single slit interference

    I was just wondering if anyone was aware of a good explanation or physical cause of single slit interference that doesn't involve the Huygens-Fresnel principle. To me, the principle is not very intuitive, light does not eminate from other light (as far as I know). I think I understand that the...
  46. Maxo

    Single slit interference picture

    I'm wondering something about illustrations of single slit interference. I've seen them being illustrated in different ways. One way is this: and another way is this: But I don't understand how these can show the same thing? In the first picture, we have light rays that are obviously NOT...
  47. D

    Complementarity with single slit diffraction

    Sometimes I see complementarity explained as being not able to measure any wave and particle property at the same time. But it looks like in a standard double slit experiment the detector measures both particles as the interference, so the wave. The same with a single slit. If a photon is...
  48. S

    Intensity of single slit vs double slit

    Homework Statement Light of intensity I0 passes through two sets of apparatus. One contains one slit and the other two slits. The slits have the same width. What is the ratio of the out going intensity amplitude for the central peak for the two-slit case compared to the single slit?Homework...
  49. P

    Single Slit Diffraction effects

    I know that a smaller width of a gap would lead to "more diffraction", and diffraction effects are at their peak when the wavelength of the diffracted waves is equal to the gap width. But what if the gap were smaller than the wavelength? Can someone describe the diffraction pattern (if any) that...