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. A

    How does polarization take place by reflection?

    i wonder how it's possible that due to reflection from water say of light only perpendicular components remain and others are refracted.
  2. P

    Diffused Sun/Moon Reflection: Why Water Appears as Columns

    How would the reflected light from the sun or moon apear if the water surface were perfectly smooth?and why does reflected light from the sun or moon appear as a column in the body of water like here http://www.free-slideshow.com/screens/waves_sunsets/sun-over-the-ocean.jpg
  3. P

    Exploring Free Electron Reflection of Photons

    How do free electrons of metals reflect photons? I had read that they first absorb and then emit the photon but if they are free (not bound to an atom and thus not fixed to any old energy level) why should they lose their energy on the first place? Surely they don't have to drop to their...
  4. A

    Why do we measure the angle of incidence or reflection

    Why do we measure the angle of incidence or reflection (or say refraction even) w.r.t normal to the surface and why not w.r.t the horizontal surface?
  5. 8

    Analyzing Reflection from an Absorbing Medium

    Homework Statement 3. Consider the reflection from the boundary between air and an absorbing medium. We can use the usual Fresnel Equations, but with a complex refractive index for the absorbing material. For various angles of incidence, use the real parts of the refractive index to...
  6. T

    Phenomena of reflection of light

    I wonder why is there a gap at the starting of the reflected light when i conduct this experiment? Can anybody explain this to me? Thanks!
  7. D

    Understanding Wave Reflection and Phase Shifts

    I've attached the multiple choice question. The first time round that I did it, I simply just did a phase shift of the whole graph by pi. Basically I just translated the whole graph by pi, resulting in option (D). However, it later came to my attention that by continuing to draw the...
  8. S

    What is the relationship between the reflection angles in a prism?

    Homework Statement For a beam of light shone on a prism, the reflected beams will give twice the angle of the prism. Homework Equations We know that the angle between the incident ray and the normal = angle between reflected ray and normal The Attempt at a Solution i tried drawing...
  9. M

    Polarized Light Reflection: Solving for Intensity

    [b]1. A person riding in a boat observes that the sunlight reflected by the water is polarized parallel to the surface of the water. The person is wearing polarized sunglasses with the polarization axis vertical. If the wearer leans at an angle of 17.0 degrees to the vertical, what fraction...
  10. H_man

    So confused about reflection from metal surfaces

    :bugeye:Hi All... I am really confused about the mechanism of loss of energy when an EM wave hits a metal surface. I always thought the reflection was due to the motion of the electrons in the metal (due to the electric field of the wave). Which suggests that resistive losses would come...
  11. M

    Plane Reflection: Finding the Reflected Vector in a Geometric Plane

    Okay so in a problem I have a vector reflecting off a mirror. I have the equation for the normal of the mirror at the coordinates where the vector of light hits the mirror. The normal of the mirror and the vector incident are in the same geometric plane. How do I find the refection of the vector...
  12. V

    General Formula For Reflection Direction

    An Example Scenario: A particle moves at 32° and collides with a wall. This wall is rectangular in nature, which means that there is both horizontal and vertical sides. On a horizontal tangent, it would work like this (sorry for ugly, not-to-scale diagrams)...
  13. R

    What is the reflection coefficient on a transmission line at a resistor halfway?

    Homework Statement If I have a coaxial transmission line, with a resistor halfway through, and another resistor at the end, how do I calculate the reflection coefficient for the spot where the resistor is halfway? Here is a diagram of what I mean. Dashes and dots are are the lines, and }...
  14. J

    Why do some materials reflect and others absorb light?

    If the question was that why are some materials opaque and why some are transparent, the answer would be found in the energy bands. If energy bands allow such transitions for electrons, that they can absorb photon, then they will absorb it, and the photon does not go through the material. If...
  15. A

    Why can wire mesh reflect radio waves for telescope dishes?

    I’ve heard that the reason radio telescope dishes can be made out of wire mesh is because, so long as the size of the holes is less than (I believe) 1/10 the wavelength of the radio wave, the wave be reflected (it will see the dish as being solid). I was wondering what the physical reason was...
  16. Jadaav

    Understanding Refraction and Reflection: A Step-by-Step Guide for Beginners

    Hey guys, I need some notes on refraction please I don't know anything on it. Also I need to how to get ( draw ) the image of an object behind a mirror step by step please. That would really help me guys.
  17. H

    Change of phase in total internal reflection

    I would like to know if there is change of phase during total internal reflection. (In particular I would like to know if I can cover copper with several microns of glass and have it reflect 200 MHz EM waves coming from water (epsilon(H2O)=80, epsilon(glass)=4)).
  18. S

    Fresnel Equations - Equal Entry/Exit Reflection

    My first (successful) post, hope this isn't silly/trivial. Also hope this is the appropriate area for optics-related questions. While debugging some code that applies the Fresnel equations to transmission of light through multiple layers of planar media, I encountered an interesting feature...
  19. C

    Reflection across a Plane

    Suppose you have the plane given by \bold n \cdot (\bold r-\bold r_0)=0 where \bold n is the normal vector to the plane which passes through the point \bold r_0. What is the reflection x' of a point x across this plane?
  20. C

    Refraction and total internal reflection

    A mixture of red and violet light is incident on a glass-air interface. The indices of refraction for red and violet light in glass are n(red)=1.52 and n(violet)=1.538. What color of light enters the air? http://www.webassign.net/cj8/q_10.gif attempt to solve: I found that the critical angle...
  21. M

    What is the reason for phase change of light on reflection from a denser medium?

    What is the explanation for the phase change of pie that occurs when a light ray gets reflected from an optically denser medium? This fact was demonstrated by the Llyod's mirror experiment, but what is the theoretical explanation for it? Thanks
  22. B

    Light Speed and Voyager Space Probes: A Reflection

    I just want to make sure I understand this clearly. Light travels at 186 000 miles/second right? So if something was 10 light years away would that mean that it would take 10 years going at the speed of light to get there? Wouldnt it be possible to make a probe go even half that speed? I don't...
  23. Z

    Product of reflection matrices without eigenvalue 1

    I'm wondering if anybody could suggest some techniques that might be brought to bear on the following problem: Suppose a finite sequence M_1,M_2,\dots,M_k of 4\times 4 orthogonal reflection matrices is given. I'm interested in determining conditions on these matrices that will guarantee that...
  24. K

    What is the Angle ϕ of the Reflected Laser Beam in Plane Mirror Reflection?

    Homework Statement A laser beam is incident on the left mirror in the figure below, in which α = 85°. Its initial direction is parallel to a line that bisects the mirrors. What is the angle ϕ of the reflected laser beam? http://www.webassign.net/knight/p23-40.gif" Homework Equations...
  25. M

    [2 problems] Transverse Waves, Superpostion & Reflection

    Question 1 1. Homework Statement The drawing shows a snapshot of a transverse wave traveling along a string at 9.6 m/s. The equation for the wave is y(x, t) = A cos(ωt + kx). At what times could this snapshot have been taken? (Give the three smallest nonnegative possibilities.)The Attempt at a...
  26. M

    Help required for surface reflection circuit (IR-LED/ PHOTODIODE)

    Hi I am new to this forum but have been interested in reading many threads and would like to know if any of the experts could help. I am looking to make a circuit that I can measure different output levels of a photodiode from the amount of "signal" reflected onto it from a particular...
  27. G

    Reflection Matrices: Verifying Orthogonality and Finding a Unit Vector

    Verify that M(theta) is orthogonal, and find a unit vector n such that the line fixed by the reflection is given by the equation n . x = c, for a suitable constant c, which should also be determined. --------------- I did the verficiation part, by multiplying m(theta) by its...
  28. C

    About current/voltage reflection in a long coaxial wire.

    If I have a long coaxial wire with open end and apply a short voltage pulse, that pulse begins propagating through it until it reaches the end. Then, it reflects back to where it came from. I understand that it behaves like a normal wave, maintaining its energy and bouncing when it reaches a...
  29. B

    Clarifying the rules of Reflection

    I have searched topics like reflection forum and I always seem to get different answers. I'm hoping to reconcile all of this, I've read FAQs, threads, wikipedia... To explain reflection I've heard these 3 explanations: 1) Light is absorbed by an atom, then re-emitted at a later time randomly...
  30. D

    Understanding Specular Reflection: QED Explanation & Material Differences

    What is the QED explanation for specular reflection of light ? I mean, if photons interact with electrons, and a photon is re-emitted, I assume it can be emitted in any direction whatsoever. So this might work great for diffuse reflections. But what about specular reflections? How are they...
  31. J

    Refraction Defraction Reflection

    A laser beam traveling in air strikes the mid- point of one end of a slab of material with index of refraction 1.45 as shown in the figure below. Dimensions of Block 46mm (L) and 3.4mm (W) Initial ray of light enters the slab from the left side at an angle of incidence of 39 degrees...
  32. J

    Reflection loss during absorption spectroscopy

    An isotropic solid has a refractive index of 10 at low frequencies. A 10 um thick platelet of this solid with perfectly polished planes shows two absorption bands in optical transmission. These bands, corrected for reflection, have a (negative) Gaussian shape. They occur at frequencies of 3x1012...
  33. M

    Plane Wave Total Internal Reflection Problem

    Homework Statement A plane wave is incident at 70˚ to surface normal traveling within a medium with relative permittivity = 4, striking the boundary with air. Where is the nearest magnetic field max. to the boundary in the initial medium? Find the 1/e penetration depth of the evanescent...
  34. T

    Maximum Angle for Total Internal Reflection

    Homework Statement What is the maximum value of θ1 that would cause total internal reflection to occur? N1 = 1.3, n2 = 1.6 (picture attached) Homework Equations Critical angle = sin^-1(n1/n2) The Attempt at a Solution I figured the critical angle to be 54.3. That means that...
  35. P

    Photon reflection from a metal surface

    Hi, I have been looking for a better explanation of the following question in different threads, but although there are some related question, I haven't found one that answers my question. I have read in Atkins-Physical chemistry book the following (summarized) explanation about why metal...
  36. P

    Probability of specular reflection in Fuchs theory for copper

    The resistivity for thin films can be obtained using Fuchs theory \rho = \left[1-\left(\frac{3}{2\kappa}\right)(1-p)\int_1^\infty\left(\frac{1}{t^3}-\frac{1}{t^5}\right)\frac{1-\exp(-\kappa t)}{1-p\exp(-\kappa t)}\mathrm{d}t\right]^{-1} \rho_0 where p is the probability that an electron...
  37. N

    Reflection Coeff - Quantum Mech

    Homework Statement Find the reflection coefficient for electrons traveling toward a potential change from V to V_0 with a total energy E > V_0. The potential diagram is just a unit step function. It goes from V = 0 to V = V_0 at x=0. In piecewise notation: \begin{displaymath} V(x) =...
  38. S

    Angle of incidence, angle of refraction and angle of reflection

    Homework Statement A light ray strikes the surface between two transparent materials as shown. Each angle is labeled with a letter. Give the letters for the angle of incidence, angle of refraction and angle of reflection, in that order Homework Equations...
  39. S

    Angle of Incidence with partial reflection and partial refraction

    Homework Statement A beam of light in air strikes a piece of glass (n=1.51) and is partially reflected and partially refracted. Find the angle of incidence if the angle of reflection is twice the angle of refraction. Homework Equations n1sintheta1 = n2sintheta2 The Attempt at a...
  40. R

    Doppler Effect: Moving Observer riding on moving source With reflection off wall

    Homework Statement A bus is moving at 37.00m/s towards a wall. The sound from the bus has an original wavelength of 0.1500m. The sound from the bus reflects off the wall. What frequency sound does an observer on the moving bus hear from the reflection?? Homework Equations Moving Observer: fo...
  41. C

    Do photons really bounce and bend? A question for physicists

    I am not a physicist but I do have a non-mathematical science background and I am a serious physics appreciator. I am new to this site and have a pressing question I would like to ask a physicist. High school and even college level physics texts desribe the reflection and refraction of light...
  42. C

    Solar Radiance - Reflection

    Homework Statement An underwater observer is looking directly into the sun. His head is near, but below the surface, and he is not wearingsun glasses. Let Ls(x) be the solar radiance at the water surface, on the air side, when the sun is at a zenith angle x. What is the ratio of the solar...
  43. S

    Calculate Distance Light Travels in Reflection from Light Fibre

    Homework Statement A ray of light enters a light fibre so that it hits the side at an angle of 16° with the long axis of the fiber, . Calculate the distance the light ray travels between successive reflections off the side of the fibre. Assume that the fibre is 1.03x10-4 m in diameter...
  44. K

    Reflection coefficient of the step function potential

    Homework Statement Consider the step function potential: V(x) = \{ \begin{array}{*{20}c} {0,(x \le 0)} \\ {V_0 ,(x > 0)} \\ \end{array},Caculate the reflection coefficient,for the case E<V0,and comment on the answer Homework Equations - \frac{{\hbar ^2 }}{{2m}}\frac{{d^2 \psi...
  45. M

    RF reflection from ground through dense snow

    Hello all I work at a BC Ski-hill... what I need is a method to quickly but accurately measure the depth of dense snow (man-made snow, some might call it ice). Traditional method of mechainically boring through to ground is slow, inaccurate & messy. New GPS based methods require detailed gps...
  46. Q

    Relativity - Doppler effect in reflection from a moving mirror

    Homework Statement A plane mirror is moving at a uniform speed v away from the observer and a pulsing source of light of frequency f_0. What is the frequency of the light reflected in the mirror as seen by the observer? This isn't an actual homework question but I have a similar...
  47. J

    Astronomy Reflection nebula Question

    Homework Statement 1. If you looked at the spectrum of a reflection nebula, would you see absorption lines, emission lines, or no lines? Explain your answer. As part of your explanation, describe how the spectrum demonstrates that the light was reflected from nearby stars. Homework...
  48. M

    Reflection of a 2-d shape about some line

    I've noticed the the reflection of a 2-d shape about some line is the same as rotating it by 180 degrees about that line, where it rotates through the third dimension. Does this generalise to higher dimensions? I hope it's clear what I mean here.
  49. L

    Can Moving an Object and a Lens Create a Virtual Image?

    Homework Statement Is it possible to move an object and a lens in such a way that the image is virtual? The Attempt at a Solution Well I could use a convex lens, and shine a light into it, then something would happen. The light would be angled up or angled down (depending on the...
  50. N

    What Software Can Simulate Light Reflection for a Solar Heliostat Project?

    Does anyone Know a program that can simulate light reflection in a 3d environment, to help me in my project "Solar Heliostat". I want the program to determine the angle of reflection and the size of the beam of light on the desired target.
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