What is Reflection: Definition and 953 Discussions

Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves. The law of reflection says that for specular reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected. Mirrors exhibit specular reflection.
In acoustics, reflection causes echoes and is used in sonar. In geology, it is important in the study of seismic waves. Reflection is observed with surface waves in bodies of water. Reflection is observed with many types of electromagnetic wave, besides visible light. Reflection of VHF and higher frequencies is important for radio transmission and for radar. Even hard X-rays and gamma rays can be reflected at shallow angles with special "grazing" mirrors.

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  1. P

    Why angle of incidence equal to angle of reflection

    I want to why in ray optics. Angle between incident ray and reflecting surface normal is equal to angle between reflected ray and reflecting surface normal. Simply why angle of incidence is equal to angle of reflection?
  2. R

    Absorption of light in a mirror

    I read in some place that the mirror be it 100 per cent reflective, will also absorb if a light strikes to it. Is it true? what does it absorbs?
  3. aditya ver.2.0

    The Wave-Particle Duality of light and the laws of reflection

    I wonder how the wave particle duality property of light persists with the laws of reflection? How exactly is a photon directed in the same angle (i.e. the angle of incidence) by a particle as reflection while abiding through the quantum theory and the Raman Effect? Such as we throw an elastic...
  4. PhysicsStudnt

    Why does a phase shift occur on reflection?

    Dear Experts, When an electromagnetic wave moves from a rarer to a denser medium or gets reflected by a mirror, it encounters a phase shift of pi or (lambda/2), in that case, the reflected wave will be out of phase with the incident wave. I have a very basic (maybe non intuitive or even...
  5. B

    Reaction force direction during reflection

    I have a simple question let's say object hits the wall at angle and reflect. Will reaction force from that impact exerted on wall be red line or green line ? ( I would like explanation why in each case)
  6. M

    Wave reflection in Closed End Wind Instrument

    Hi, I am a little confused with the phase change that occurs in closed end wind instruments. According to http://newt.phys.unsw.edu.au/jw/flutes.v.clarinets.html, the phase does not change when the sound wave reflects off the closed end of the instrument. I thought that the phase changes by 180...
  7. J

    How Does Polarization Change Upon Reflection and Refraction?

    http://en.wikipedia.org/wiki/Brewster%27s_angle The dipoles that produce the transmitted (refracted) light oscillate in the polarization direction of that light. Why? Does that last sentence actually say no light is reflected back if the angle of impact is orthogonal to the surface?
  8. T

    Light Through Glass: Exploring Reflection and Refraction

    Hi everyone! Just wondering why when light hits glass it can pass through and be reflected at the same time. I'd like the classical and quantum explanation if possible. Also try to keep it simple. Thank you!
  9. S

    Maximum critical angle for total reflection?

    Homework Statement A beam of light is incident on the boundary between a piece of glass to air. The index of refraction of the piece of glass is 1.4. Find the critical angle. It is quite simple to figure out this problem. Sinpheta critical = n2/n1 (as long as n1 is greater than n2)...
  10. R

    Reflection from Thin Films Plot

    Homework Statement Here is a plot of Reflectance vs Wavelength from a multilayer thin film stack of alternating high and low refractive indices: I want plot this in Matlab, but what equation was used for this plot? The diagram is from my textbook, there are many like it online but...
  11. S

    Total internal reflection: Question on angle of reflection.

    Homework Statement Suppose light from is moving from water to air. The critical angle be θ i.e. for angle of incidence θ, the angle of refraction is 90°. Refractive index of water wrt air be μ. Suppose the angle of incidence (i) is increased by 1° to θ+1. What happens to the...
  12. D

    Optics: Find n for Proportionality of Concave Mirror Image to R^n

    The size of image formed by a concave mirror is proportional to R^n where R is radius of curvature. Find n. Cannot understand how to proceed. Need help.
  13. ShayanJ

    Calculation of reflection coefficient

    I've got a problem asking for the reflection coefficient of a system consisting of a ideal conductor covered with a thin layer of lossless dielectric. I just don't know what to do.How can I do it? Thanks
  14. A

    Reflection laws applied on mirrors

    Hi Forum, Simple question here, but one that has been bugging me. Please look at picture. So, rays from the baseball can go from the lower mirror to the eye. (1 image) Rays from the baseball go from the upper mirror to the eye. (1 image) Rays from the baseball go from the lower mirror to...
  15. R

    Osmium Alloys and UV reflection

    So I was reading that Osmium will break down into a poison oxide gas if it is heated in the presence of air. If Osmium is blended into an alloy will that eliminate its ability to oxidize in such a manner. I have been looking at Osmium as a UV reflective material but poison gas break down is...
  16. D

    Orthogonal operator and reflection

    Homework Statement Let ##n## be a unit vector in ##V## . Define a linear operator ##F_n## on ##V## such that $$F_n(u) = u-2\langle u, n \rangle n \; \mathrm{for} \; u \in V.$$ ##F_n## is called the reflection on ##V## along the direction of ##n##. Let ##S## be an orthogonal linear operator on...
  17. P

    Infrared absorption reflection and defraction

    Please tell me about common materials which absorb IR sunlight radiation in the band of spectrum 1.1-2,5 microns and which will not allow the penetration of IR if some surface is covered with thin layer of them ?
  18. A

    Transmission and reflection of waves at boundaries

    Homework Statement An infinite string is made of three sections, a single intermediate section of length a and density p1 between two semi-infinite sections of density p2. A wave of frequency f is incident on the intermediate section. If a is an integer multiple of the wavelength in that...
  19. T

    Point reflection vector

    Please excuse my terminology as I am teaching myself linear algebra. I am attempting to construct a vector which can provide reflection from the origin, eventually I want to be able to move this point of reflection anywhere (translation and rotation) but I'm starting at the origin since that is...
  20. F

    Why do dark objects feel hotter than reflective objects?

    Dear Forum, An object, like a metal, that is highly reflecting (white body) is very different from a very emissive object (black body). An object that closely behaves like a black body absorbs all the incident radiation. But it also "emit" all the absorbed radiation (over a range of...
  21. O

    EM Wave Reflection: Why Parabolic Reflectors Differ from Mirrors

    Why do parabolic reflectors for microwaves (e.g. satellite TV) not reflect light like a mirror? Why do things like spoons, which are presumably conductive, reflect light? Thank you
  22. J

    Reflection at a spherical surface

    Homework Statement An object 0.6cm tall is placed 16.5cm to the left of the vertex of a concave spherical mirror having a radius of curvature of 22.0cm. Determine the position, size, orientation and nature of the image. Homework Equations \frac {1}{S} + \frac {1}{S'} = \frac {1}{f} =...
  23. M

    Didn't Newton's corpuscular theory fail to explain reflection?

    In 1637 Descartes gave the corpuscular model of light and derived Snell's law. This Corpuscular model of light was further developed by Isaac Newton in his famous book entitled OPTICKS and because of the tremendous popularity of this book, the corpuscular model is very often attributed to him...
  24. I

    Why in Optics total internal reflection happens this way?

    why total internal reflection happens only when a beam of light travels from a medium with higher index of refraction to a medium with lower index of refraction and not the other way around (i.e from a medium with lower index of refraction to a medium with a higher one)?
  25. A

    Does polarization change upon reflection?

    A simple question: is the polarization of light affected in any way upon reflection? What about upon refraction/diffraction? What interactions affect polarization?
  26. S

    Magnetic Field Reflection from a Media Interface

    Say there is an electric field oriented along the x-axis and is propagating along the z-axis. A medium exists from z>0. The fields for z<0 can be written as I'm confused on the negative sign of the reflected magnetic field.
  27. N

    What is the range of angles for total internal reflection in glass?

    [b]1. Light traveling in air strikes a glass surface with n = 1.48. For what range of angles will total internal reflection occur? [b]2. sinΘc = n2/n1 [b]3. I did this equation with air as n2 and glass as n1 and then got Θc=42.5°. After that I subtracted that from the normal (90°)...
  28. M

    Reflection of Light by Oil on Water

    Right, so, I am new to this, so please excuse me if I make a glaring error. Say there is can of water with a layer on oil on the surface. Light (of lambda=590nm) is shone straight down on the oil. How do I find out the thickness of the oil layer that would most strongly reflect the light?
  29. H

    Inconsistent Reflection and Transmission values-step potential & E < V

    I can show that for a step potential and E < V, that the wave function is fully reflected and has no transmission into the potential interval (interval 2), x =0 at interval boundary, by Wave equation for interval 1: Ψ1 = A1eik1x + B1e-ik1x Wave equation for interval 2: Ψ2 = A2eκ2x...
  30. NATURE.M

    Phase constant and reflection of waves

    Homework Statement If two waves are created at x = 0 and t = 0 (and are in phase to begin with), and are then sent traveling along a string in the positive x direction, and they get reflected at the end of the string, there will be a similar pair of waves traveling in the negative...
  31. H

    Light - reflection in two facing mirrors

    Hi, thanks for stopping by.I'm studying for an exam tomorrow, I would really appreciate even just a push in the right direction! Homework Statement A plane mirror and a convex mirror are placed facing each other and 50 cm apart. A candle is placed on the principal axis 20 cm from the plane...
  32. G

    Frustrated total internal reflection: Where does energy come from?

    Hi, When we have total internal reflection of light at the boundary of an optically dense to an optically thinner medium, one can show that the component of the Poynting vector perpendicular to the boundary is zero, i.e. there is no energy flow into the thinner medium. However, the electrical...
  33. M

    Optics: white object reflection properties

    If a red light drops on a red object, we know that all of the red light is reflected, and none is absorbed. But what happens if a red light drops on a white surface, is all of the red light reflected, will the intensity of the reflected light be the same? Or will the reflected light be of a...
  34. E

    MHB The Reflection Property of a Hyperbola

    Hello, Does anyone have a reference to a proof of the reflective property of a hyperbola? I need a proof that uses the geometric definition of a hyperbola as the locus of points $X$ such that $|XF_1-XF_2|=2a$ for some fixed points $F_1$ and $F_2$ and a positive constant $a$. The proof may also...
  35. E

    Why doesn't my convex mirror reflection match the expected focal point?

    Homework Statement For self study, I've been trying to understand my convex mirror. Some online instruction I've been following states that if an incidence ray (red line in my model, below) parallel to the principal axis (black line) hits a convex mirror (full curvature outlined in black...
  36. B

    Reflection of sound. Changes to its properties.

    Hi guys and girls, Just had a question I have been thinking about for a while. Suppose you have a sound maker than makes a pure tone at a particular frequency. You play this tone for an instant directed directly at a flat wall (not absorbent at all). If you could measure the reflected tone...
  37. Entanglement

    Reflection, transparency and Absorption

    What are the properties that make materials reflect or absorb a certain EM wave or just allow it to pass through ( transparency ) ??
  38. H

    Lens Reflection: Does Light Bounce Off?

    When a passing through a lens,will there any reflection on the surface of it?
  39. S

    Reflection of Laser on mirrors

    Question link: http://gyazo.com/4d52ab2521e5b222241718ea1b7ccb08.png I have to solve this using vectors, not geometry My professor said the equation that's required is -v* = 2 proj v onto n - v and v* is reflected vector, so I don't really understand how to do this First off I don't...
  40. PsychonautQQ

    Crystalline Bragg Reflection

    Homework Statement The bragg angle for reflection from the (110) planes in bcc iron is 22 degree's for an x-ray of wavelength = 1.54 angstroms. Compute the cube edge for iron. Homework Equations 2dsinθ=nλ ? The Attempt at a Solution I feel woefully underprepared for this problem and...
  41. X

    Length of coaxial cable, based on signal reflection

    Homework Statement We measured the time between a signal source, and it's reflection coming back through our probe after going through an open-ended coaxial cable. My teacher told us this: the cable has a polyethylene insulator between central wire and the grounding web, which has a...
  42. U

    Total internal reflection for a long time

    Imagine a square prism made from some material with such an index of refraction and surrounded by a substance of such index of refraction so that light rays entering the prism and hitting one of the internal sides of the prism at an angle of incidence 45° experience total internal reflection...
  43. U

    What is the Relationship Between Impedance of Dielectric and Material?

    Homework Statement Part(a): Show relation between impedance of dielectric and impedance of material: Part (b): Show the ratio between reflected and incident amplitude is: Part (c): Three layers now from left: vacuum, dielectric 2 sandwiched inbetween, and dielectric 1. Part (d)...
  44. S

    [FDTD/Fotran] detected reflection near boundary but don't know why

    hi all, i have wrote codes for 2d fdtd in different permittivity (epsilon). in this code, cell size is 200 x 200, start with eps=1 from center, and different permittivity started at boundary (i1,i2) = (25,75) = (j1,j2), epsilon = 2. the problem is, when the wave propagates and approach...
  45. D

    PHYSICAL explanation of light reflection by metals

    Electric field of an electromagnetic wave incident on a metal accelerates free electrons, and these accelerating electrons then emit radiation opposite to the electric field of the wave, thus reducing the resultant amplitude in the forward direction. Radiation emitted in the backward direction...
  46. S

    Feynman on Reflection: Exploring Time & Direction

    I have been reading the explanation of reflection that Feynman provides in The strange theory of light and matter. There are two things I do not understand: a) How does he choose the directions of the little arrows below the diagram? I understand that each path is different in that it...
  47. S

    X-ray diffraction or reflection?

    In x-ray diffraction , even though its reflection is happening , we call this as x ray diffraction. why is it so?? i don't know whether it has been discussed previously here.
  48. E

    What is the maximum reflection angle in the Chandra X-ray telescope optics?

    Homework Statement Hi! I'm having a problem with one assignment and I would really need som help. The question is: The Chandra X-ray telescope is used for observations in the 0.1-10 keV range. Focal length is 10 m, max mirror radius is 0.6 m. What is the largest reflection angle in the...
  49. L

    Why does a change in impedance cause reflection?

    why does a change in impedance causes reflection? I know that R=(Z2-Z1)/(Z1+Z2), but what is it that makes the wave be reflected? thanks
  50. E

    What is the largest reflection angle in the Chandra X-ray telescope?

    Hi! I'm having a problem with one assignment and I would really need som help. The question is: The Chandra X-ray telescope is used for observations in the 0.1-10 keV range. Focal length is 10 m, max mirror radius is 0.6 m. What is the largest reflection angle in the optics (assuming...
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