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. M

    Equations for total internal reflection

    If a beam of light undergoes total internal reflection, are there any equations to determine the angle of reflection based on the angle of incidence? Snell's Law: ## n_1sinA = n_2sinB ## is to my knowledge only valid under medium-to-medium transmission (for B: [0, pi/2]), correct? If total...
  2. F

    Standard matrix for reflection across the line y=-x

    Homework Statement Let T : R2→R2, be the matrix operator for reflection across the line L : y = -x a. Find the standard matrix [T] by finding T(e1) and T(e2) b. Find a non-zero vector x such that T(x) = x c. Find a vector in the domain of T for which T(x,y) = (-3,5) Homework EquationsThe...
  3. M

    EM wave interacting with refelcting surface

    When trying to explain reflection through the EM treatment of light waves, how do we account for the fact that the electric/magnetic field of the incoming light would penetrate into the medium from which it is reflecting off of? Diagrams like these: show the 'reflection point' on the axis of...
  4. A

    Fiber Bragg Gratings Reflection Co-efficient

    I am studying fiber bragg gratings for a project. I read the couple-mode theory and came across a plot of the reflection coefficient v/s wavelength used which had a global maxima at the Bragg wavelength. The plot was drawn for a constant value of the coupling constant κ. I don't understand this...
  5. D

    Can Coherent Light Waves Interfere with Each Other?

    If two beams of light, in a vacuum, are projected towards each other will the beams be reflected ? If not what will happen ?
  6. 2

    Stargazing Understanding the Field of View of Reflecting and Refracting Telescopes

    I don't quite understand the concept of field of view of a telescope... Specifically, I am trying to understand the advantages of reflecting and refracting telescopes compared with the other, and my textbook says that "Refracting telescopes have a wider field of view than reflectors of the same...
  7. F

    Determine attenuation of voltage in transmission line

    Hello, So I have a circuit where I input a square pulse with a source impedance and load impedance (which are just pure resistors) each of which can be varied and a transmission line circuit connecting them which is made up of resistors, capacitors, inductors in a lumped element model. I set...
  8. RaulTheUCSCSlug

    Solving index of refraction for Total Internal Reflection

    Homework Statement Homework Equations Snell's Law n1sin(theta_1)=n2sin(theta_2) Total Internal Refraction: sin(theta_c)=(n_2/n_1) lambda_n=lambda_n The Attempt at a Solution So I drew the triangle and this is what I got, and well here is just a picture so far of what I have. [/B] I've...
  9. c3po

    Find matrix representation for rotating/reflecting hexagon

    Homework Statement Consider the set of operations in the plane that includes rotations by an angle about the origin and reflections about an axis through the origin. Find a matrix representation in terms of 2x2 matrices of the group of transformations (rotations plus reflections) that leaves...
  10. J

    The Law of Reflection and Lasers

    So I've been looking into the Law of Reflection with Specular and Diffuse Reflection. I understand that electrons have a certain vibrational frequency in objects, and if a light wave matches that, that color wouldn't be observed. My question is, what if I took a red laser pointer and shined it...
  11. R

    Does reflection change the frequency of light?

    Note that I am not addressing only specular reflection here, but both kinds. Anyway, so if I had light of a certain frequency incident upon a surface, will the light that reflects off that surface also have the same frequency? That would imply that it had retained the full 100% of its energy...
  12. S

    What is the correct way to draw this internal reflection

    image upload no size limit http://postimage.org/][/PLAIN] image hosting adult The answer is saying the following, initial reflection + 0 or 1 further reflection only, not at lower surface must be straight and reach within 1cm of end. --------- How come 0 or 1 reflection only ? The length...
  13. nmsurobert

    Minimum Energy for Bragg Reflection in Cubic Crystals

    Homework Statement A cubic crystal has a spacing between atoms of d = 0.2 nm. What is the minimum energy for X-rays such that non-trivial Bragg reflection may occur (peak with n =1)? Write your answer in units of keV. Homework Equations 2dsinθ = nλ The Attempt at a Solution i have no idea...
  14. ShayanJ

    Why Does Reflection Phase Shift Not Always Apply to Both Polarizations?

    Its always said that a reflected light ray acquires a phase shift equal to ## \pi ## if ## n_1 < n_2 ##. But considering the Fresnel coefficients, its revealed that its only for the s-polarization reflection coefficient that ## n_1 < n_2 ## causes the coefficient become negative. The...
  15. C

    MHB Reflection Matrices: Find Components of R

    Hi there, I've got a unit vector u^, arbitrary vector v, and a vector w which is the reflection of v in a line in the direction of u. I have already proved that w= 2 (u^.v)u^ - v. However, the next part of my question asks me to write w= Rv and find the components of the matrix R, taking the...
  16. S

    What is the index of refraction of the glass in this reflection problem?

    Homework Statement Unpolarized light hits a flat glass surface, 37.5 degrees to the surface's normal. The reflected light's polarization is investigated with a polaroid. The relationship between the max and min value of intensity from the polaroid when it is rotated is 4.0. What is the index of...
  17. W

    Understanding Bragg's Law and Reflection: A Beginner's Guide

    I don't think I understand Bragg's law, but I'd quite like to! There's loads of stuff online, but most of it is too complicated for me as a first year undergrad. My understanding was that x-rays get diffracted, but then my textbook says something about electric dipole moments (never heard of...
  18. S

    The ratio of the distance of the focus and the point

    1. The problem statement: A ray of light is incident on a concave mirror. It is parallel to the principle axis and its height from principle axis is equal to the focal length of the mirror. the ratio of the distance of point B to the distance of the focus from the center of curvature is( AB is...
  19. S

    The time span for which insect can see its image?

    1. The problem: A plane mirror of length 2m is kept along the line y=-x as shown in the figure. An insect having velocity of 4 cm/s is moving along x-axis from far away. The time span for which the insect can see its image will be:A)50 sec B)25 sec C)25√2 sec D)50√2 sec 2.The answer...
  20. W

    How do similar triangles help determine the visible area in a plane mirror?

    Homework Statement How much of a wall 3m behind you can be observed in a 5 cm square mirror which is held centrally at a distance of 10 cm from your eye? Homework Equations None that I can think of. I think this is straight geometry. The Attempt at a Solution I know I have to use similar...
  21. R

    Angle of incidence and reflection

    I am trying to write a java code where the user inputs the height at which a solid body approaches a sphere of radius R and outputs the angle ##\theta## at which the body bounces off the sphere. I have all my code written is just that I don't know how to derive the equation that calculates the...
  22. N

    Reflection - TE and TM phase plots

    Hello everybody, I want to confirm that the following plot is correct, especially with regards to how the phase changes after the critical angle. The professor at my school confirms its correct, but after reviewing the relations, I get an opposite shift for the TE wave. So can you confirm...
  23. C

    Orthogonal projection and reflection (matrices)

    Homework Statement [Imgur](http://i.imgur.com/VFT1haQ.png) Homework Equations reflection matrix = 2*projection matrix - Identity matrix The Attempt at a Solution Using the above equation, I get that B is the projection matrix and E is the reflection matrix. Can someone please verify if this...
  24. B

    MHB Sketch of the Reflection Transformation of a Parallelogram

    $\textbf{Problem:}$ Let $T: \mathbb{R}^2 \rightarrow \mathbb{R}^2$ be the linear transformation that reflects each point through the $x_2$ axis. Make two sketches that illustrate properties of linear transformation. $\textbf{Solution:}$ Let $T(\textbf{x}) = \begin{bmatrix} -1 & 0 \\ 0 & 1...
  25. P

    Light rays reflected off vertical mirror (law of reflection)

    Homework Statement A vertical mirror is placed at the origin. A ray of light coming from A is reflected by the mirror so that it passes through B. How far from the bottom does the ray hit the mirror? The coordinates are A = (11.4, 15.9) and B = (15.9, 4.7), in centimetres. Homework...
  26. W

    Clockwise rotation of the reflection coefficient w/ frequency

    It is always considered that the evolution of the input reflection coefficient, ρ, of a LTI causal passive system with frequency, f, always presents a local clockwise rotation when plotted in cartesian axes (Re(ρ), Im(ρ)), e.g. in a Smith chart, as shown in the attached figure. It must...
  27. W

    Rotation of the reflection coeff. at Smith Chart w/ frequency

    It is always considered that the evolution of the input reflection coefficient, ρ, of a LTI causal passive system with frequency, f, always presents a local clockwise rotation when plotted in cartesian axes (Re(ρ), Im(ρ)), e.g. in a Smith chart, as shown in the attached figure. It must...
  28. T

    Feynman's QED lectures: quickest path and reflection

    Feynman's first topic in his second lecture on QED is the nature by which light reflects off of a mirror. We work in ##\mathbb{R}^2##. Suppose we have a light source sitting at ##(-1,1)## and a photomultiplier sitting at ##(1,1)##, with a mirror along the x-axis. We also place a block between...
  29. Z

    Parabola incoming ray not parallel to axis

    If incoming light to a parabola is parallel to the central axis the light is reflected through the focal point and the back to its source. What about light coming in not parallel to the central axis. What path do these rays take?
  30. K

    Reflection coefficient calculation

    Hi there, I am wondering how to calculate the reflection coefficient of walls upon incident light versus wavelengths,, thanks
  31. lovethepirk

    What is the reflection angle of a golf ball after being struck by a putter?

    I'd like to begin by ignoring friction and center of gravity at the moment if that is possible...and throw out any other variables until I get the larger picture down and then I'd like to ask for a discussion including those items... The picture shows a block moving towards a ball...similar to...
  32. gracy

    What is the difference between standing waves and reflection in waves?

    I don't know from where this type of image corresponds to standing waves? http://www.stmary.ws/high school/physics/home/notes/waves/img7A.gif As at any point of time either original wave would be present or it's reflection as when the original wave would reach and hit wall then only it would...
  33. M

    Thin film interference reflection

    Homework Statement A coating of n1 = 1.27 material is to be added to n2 = 1.50 glass, in order to make it "irridescent." a) What is the thinnest layer of material which will have a reflection maximum for normal-incidence light at BOTH 400 and 600 nm (vacuum) wavelength? b) This thickness will...
  34. S

    Reflection maximum of material

    Homework Statement A coating of n1 = 1.33 material is to be added to n2 = 1.50 glass, in order to make it "irridescent." a) What is the thinnest layer of material which will have a reflection maximum for normal-incidence light at BOTH 400 and 600 nm (vacuum) wavelength? b) This thickness will...
  35. P

    Reflect Cosmic Rays: Materials for Mirrors

    Just being curious. I was wondering what kind of material you could use to reflect a cosmic ray like visible light to a mirror. It would probably pass right through it, but I was just wondering. =P
  36. X

    Why is my reflected trajectory not the expected direction of [0,0,-1]?

    I am writing a simulation in MATLAB of particles that perfectly reflect off of a surface. However, my question is physics based, not code based. So here is my issue. A particle is traveling towards a flat plane in space at z=1 with a velocity vector of [0,0,1]. The normal vector of the...
  37. C

    Transmission Lines: Reflection Coefficient vs Frequency

    Hey guys - I've been using this website to study transmission lines. (great study aid - posting for others to use. Great for smith charts) However, I've noticed this graph they have for load matching: I'm having trouble finding or understanding a relationship for reflection vs frequency...
  38. H

    Reflection and refraction with equal refractive indices?

    The Fresnel equations indicate that radiation will be 100% transmitted if two mediums have the same refractive indices. If that is true, then whey is there so much reflection off of, for instance, cracks in glass? Is this because there is a microscopic vacancy where the index of refraction...
  39. R

    Simple (?) question regarding reflection of light

    Does natural light when it hits an object cause transition of electrons between energy states and depending on the chemical composition of the material (hence the size of the transition) determine which colour we see? So everything around us is emitting light (photons)? Everything around us is...
  40. Ookke

    Light reflection in length contracted system

    Light beam hits the mirror perpendicularly and returns to the source (left picture). The same system in horizontal motion (right picture) is skewed due to length contraction so that both beam and mirror are at higher angle. Because the beam returns to source in the system's rest frame, it must...
  41. U

    Reflection and phase difference

    Homework Statement Hi, This is not a homework question. I have my exam for my physics unit tomorrow. I am pretty set for it except for questions of this type. Can you please show me how I can get the answer? Thanks [/B] Homework Equations N/A The Attempt at a Solution N/A
  42. Algr

    Finding Optimism in Big Hero 6: A Reflection

    In reference to sarcasm in another thread, no it is NOT as good as Interstellar. But it was a quite good film for the most part. It actually shares the optimism about the future that is much needed lately, as well as a fairly realistic picture of what science development is like. (Compared to...
  43. K

    Why does reflection of EM waves not also cause transmission?

    I understand that reflection of EM waves is the electrons on the surface of an object being caused to oscillate, and transmission is the electrons all the way through the object being caused to oscillate. Why, in reflection, when the electrons on the surface of an object are caused to...
  44. L

    Fresnel's Equations: Reflections and Total Internal Reflection

    I am trying to understand the derivation behind the equations for the phase shift incurred when light hits an interface between two lossless dielectrics under total internal reflection (TIR) from what I gathered in S. O. Kasap's Optoelectronics and Photonics. On the final pair of pages...
  45. H

    Confusion regarding Standing Waves and Reflection resulting in Phase Change

    So a standing wave is one which looks to be standing still at certain harmonic frequencies. At these frequencies, when the wave reflects off the end, it will undergo a phase change of 180 degrees. This creates constructive interference as shown below: In the case of a wave on a string, since...
  46. Q

    If I travel at the speed of light and have a mirror can i see my reflection? Thanks

    If I travel at the speed of light and have a mirror can i see my reflection? Thanks Any ideas?
  47. H

    Transmisson and Reflection (Quantum)

    Homework Statement Suppose a 12.0eV electrons approach a potential barrier of height 4.2eV. For what barrier thickness is the reflection at a maximum? Known: v_0=6.7*10^(-19)J E=1.9*10^(-18)J m=9.11*10^(-31)kg hbar=1.055*10^(-34)J*s (I have converted from eV to J to make the units...
  48. D

    Theoretical 100% Light Reflection Room

    If there was a room with all walls that are 100% reflective and a light source. If you were to instantaneously remove that light source, would the room still be lighted? If yes, if an object and the light source were previously present the room, and were to be instantaneously removed, would the...
  49. E

    Ray A Reflection & Emergence: True or False?

    Homework Statement The net deviation of ray A(Figure(i))) in counter clockwise direction after one reflection and emergence is 180+2i-4r (True False) Homework Equations The Attempt at a Solution I don't know how to begin to solve this problem, so there is no attempt at a solution.
  50. R

    Why Does a Wave Reflect with Double Amplitude at a Free End?

    Hi everyone, the fact that a wave reflects from a string when it's end is free and the end of the string rises to a height of 2A seems to confuse me a bit. Even though I find it somewhat intuitive I would appreciate a detailed explanation of the same. Thanks in advance.
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