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. C

    Reflection and Absorbtion of Microwaves, also Masers

    I have tried searching for answers to these questions but i can't seem to find them, so if anyone could help me it would be greatly appreciated. How efficiently you can reflect microwaves? I know visible light can be reflected at 99.99% efficiency or something ridiculous like that, is it the...
  2. T

    Step potential - question about reflection coefficient

    Hi. I've been trying to understand the phenomenon of step potential, when energy of particle E is higher than the potential V. Then we have solution on both sides of boundary in the form of wave functions... Is the reflection coefficient in this case simply (E-V)/E ?? Can anyone show me a...
  3. jaketodd

    Angled electron reflection, coherency

    Is it possible to reflect an electron wave at an angle while maintaining coherency throughout the process? I found this but I don't think it talks about coherently reflecting *at an angle*: http://eprints.ecs.soton.ac.uk/16241/1/paper_16.pdf Thank you!
  4. A

    Angle of incidence, reflection, and refraction

    Homework Statement What are the difference among angle of incidence, reflection, and refraction when light strikes two parallel surfaces? What does it mean "light is incident on film"?-is that the angle of incidence? The Attempt at a Solution I know how to find all of...
  5. W

    Reflection Principle(PDES)

    Can someone explain to me why do we use this for boundary conditions in the heat, and wave equations? Why must we make an odd extension of our initial data and not even?
  6. W

    Fresnel Reflection and Transmission Coefficients

    Hi all, The relation between the magnitudes of the incident, reflected and transmitted waves are obtained using Fresnel coefficients. If a field moves from air to a more denser medium, which field should have a greater magnitude (reflected or transmitted)? I thought that it would be the...
  7. W

    Reflection and Transmission of EM waves

    Hi all, I was reading "Geometrical Optics Reflected Fields" chapter from "Introduction to Uniform Geometrical Theory of Diffraction" textbook. The author assumed that the surface is perfectly conducting and therefore he only considered the reflected waves. He derived a formula for the...
  8. B

    Light reflection by traffic light after rain

    Hi. I need to write up a short one paragraph on a picture I took-- I just need hints or suggestions so I can go and research the effect myself. Any insights would be greatly appreciated. I have a picture of a traffic light (red). The ground is wet after rain. The red light is smeared out...
  9. L

    Solving Reflection Matrix Homework: Angle & Rotation About Origin

    Homework Statement Given the matrix A= -1/2 root(3)/2 root(3)/2 1/2 determine if the matrix is a rotation about the origin or a reflection about the positive x axis and find the angle between the that the line makes with the x-axis Homework Equations The...
  10. B

    Reflection and transmission of waves

    Homework Statement A river canyon is 147 m across as shown in Figure P.32. You are located on the river surface and clap your hands once to generate a brief acoustic pulse. You detect a time interval of 0.407 s between the twin echoes recorded on tape, analyzed when back home (?) in a...
  11. A

    What Is the Minimum Index of Refraction for Total Internal Reflection?

    Homework Statement The prism is replaced by a new prism of the same shape, which is set in the same position. The light beam experiences total internal reflection at the right surface of this prism. What is the minimum possible index of refraction of this prism? Homework Equations...
  12. S

    Change of momentum of photon upon reflection

    1. What is the change in momentum of a photon when it bounces off a mirror? (assuming it's a perfect mirror) My guess is that it's 2h/\lambda. But i think it should be more complex than this.
  13. G

    [Q] The way of phase shifting of reflection light

    Hi, I learned optics with pedrotti optics book. It is suppopsed that light is reflected on surface of first layer and then tranmited wave is also reflected on surface of second layer, So there is Double Layer incident light get there. According to book, If two reflections are...
  14. M

    What is the minimum thickness that would minimize reflection of light

    Homework Statement A transparent film (n = 1.5) is deposited on a glass lens (n = 1.65) to form a nonreflective coating. What is the minimum thickness that would minimize reflection of light with wavelength 500 nm in air? Homework Equations 2nt = mλ n = refractive index of film t =...
  15. G

    How can I reflect a vector in a line without using the origin?

    Homework Statement To find a transformation that reflects a vector in a line that does not pass through the origin. The Attempt at a Solution I've been trying to work this out for a little while and I found that I can do it if I use the vector for the 2d transformation with a 3x3...
  16. M

    Total internal reflection in prism

    Homework Statement Light is incident normally on the short face of a 30-60-90 (degree) prism. A drop of liquid is placed on the hypotenuse of the prism.If the index of the prism is 1.68, find the maximum index that the liquid may have if the light is to be totally reflected. Homework Equations...
  17. A

    Bragg diffraction or reflection

    Bragg "diffraction" or "reflection" As you read about X-ray (or neutron) diffraction in solids, you come across authors who use the term "Bragg diffraction" and others that use the term "Bragg reflection". Some authors even use both terms in the same edition of the book (Kittel, 5th Ed.,, I...
  18. U

    Why does total internal reflection happen in glass?

    Why does total internal reflection happen in glass?
  19. R

    Optics, lenses, and light reflection

    Hi, I'm new to this place, and I'm not sure if my problem fits with this forum, but I'll give it a try. Right now, I'm building a laser range finder, but my biggest concern will be focusing the reflected laser beam onto a small silicon photodiode. And to add to that, I have barely any...
  20. B

    How many materials follows TOTAL INTERNLAL REFLECTION

    Hi all ,it is my first post so sorry if I make any mistake ,we all know about the total internal reflection in which when we passed light in any material with an angle greater than the critical angle then it will bound or catch inside the light, Now I want to prepare a list of the such...
  21. S

    Angle of reflection with moving mirror, SR

    Homework Statement A mirror moves perpendicular to its plane with speed (beta)c. A light ray is incident on the mirror from the \forward" direction (i.e., vm dot vl < 0, where vm is the mirror's 3-velocity and vl is the light ray's 3-velocity) with incident angle µ (measured with respect to...
  22. B

    Reflection and Refraction Ranking by Phase Shifts

    1. A ray of light is incident onto the interface between material 1 and material 2. There is a figure, which is a standard figure of a ray in medium of n1 striking an interface where medium2 (with n2) meets medium1. As is typical, some of the light is reflected and some is refracted. The...
  23. A

    At what angle of incidence is amplitude coefficient of reflection parallel to the inc

    At what angle of incidence is amplitude coefficient of reflection parallel to the incidence plane 0? my solution is that by Fresnell's equation, r//=tan(i-i`)/tan(i+i`)=0, i=i`,i=90.so for whatever surface,angle of incidence should be 90. is it correct? different from the answer!
  24. shintashi

    Sine wave & reflection question?

    I seem to recall it is possible to change a wave's frequency, pattern, and amplitude by adding another wave to it. Is it possible to add a second wave to a Sine wave to turn it into a cosine wave of the same amplitude and how would you do this? I'm thinking if I had an amplitude 1 for the...
  25. D

    Reflection and Refraction, much index of refraction

    Homework Statement 1. The index of refraction for water is 1.33 and that of glass is 1.50. a. What is the critical angle for a glass-water interface?b. In which medium is the light ray incident for total internal reflection?Homework Equations nisin\varthetai=nrsin\varthetarThe Attempt at a...
  26. J

    Total Internal Reflection: v1<v2, Angle of Incidence?

    Consider two adjacent transparent media. The speed of light through Medium 1 is v1, and the speed of light through Medium 2 is v2. If v1<v2, then total internal reflection will occur at the interface between these media if a beam of light is? I said incident in Medium 1 and stikes the...
  27. B

    How Do Reflections Along Different Lines Affect Point Coordinates?

    We were asked to make generalisations for the following: a.) if a point is reflected along y = x+c b.) if a point is reflected along y = -x+c i came up w/ the ff.: a.) if a point is reflected along y = x+c, then the general point (a, b) will become (b-c, a+c) b.) if a point is reflected along...
  28. V

    Value of Voltage Reflection Coefficient

    hi i was studying the "wave characteristics of transmission lines". while considering the lines with resistive termination, the term "voltage reflection coefficient(VRC)" came. With reference to the book, "Field and Wave Electromagnetics", by David K. Cheng, the following expression was...
  29. A

    Electromagnetic wave reflection

    Homework Statement A speeder is pulling directly away and increasing his distance from a police car that is moving at 29 m/s with respect to the ground. The radar gun in the police car emits an electromagnetic wave with a frequency of 8.0x109 Hz. The wave reflects from the speeder\'s car and...
  30. G

    Laser Energy Reflection: Understanding Photon Build-Up in a Vacuum

    Question, If in a vacuum, I have a laser pointing into a mirrior which bounces between two mirriors on the same spot, do the photons / laser energy continuously build up? If not whare does it go?
  31. E

    QED: reflection of light in glass

    Hello, This is my first post to physicsforums. I hope I've picked the right forum for this question, please correct me if not :blushing: To answer my question you'll have to have the book "QED, the strange theory of light and matter" in front of your eyes. I'm now reading Feynman's QED...
  32. C

    Can both a photon and it's reflection hit a particle?

    So, if you have a mirror and a particle and the source emits one photon, which one hits the particle, the photon or it's reflection in the mirror or both?
  33. D

    Reflection and the measurement, and time irreversibility

    Reflection is not considered to be a measurement. Reflection, like using lenses is considered to be a time-reversible process. It is not a measurement and it does not erase the coherence (interference pattern) Here is what I don't understand What happens to the momentum of the photon? The...
  34. C

    Reflection of light off 4 90 degree mirrors

    Hi Part 1 If I shot a laser beam into a square box where each wall is a perfect mirror and the box is filled with a vacuum and devoid of any other material that could interfere with the light beam apart from the perfect mirrors. Q/ Would that light beam continue to bounce around forever...
  35. D

    Phase shift upon external reflection

    Hello, this question might not be particularly clear, but I'd like a quantum mechanical description of the classical idea of external reflection by a medium. Now, the way I see it, a photon (or numerous photons if necessary) approach the boundary of a medium. Classically, the reflected wave has...
  36. R

    P-waves and S-wave reflection and refraction

    I am instructor for a company that does Oil well Accoustic logging. Basically we send an Acoustic pulse out and have a reciever 3' and 5' down the tool (vertically) as we log up and interpret the signal that is received back at the reciever. I was wondering if anyone can help me find...
  37. wolram

    My Kitchen Reflection Mystery: Bikes, Jumpers, and a Ghostly Shape

    My kitchen window looks into an (out house) the out house is where i keep my bikes so it is securely locked. So at night i am cooking a meal and see my reflection in the window just as clear as in a mirror. I am wearing a stripey jumper which also shows clearly in the reflection, as i move...
  38. L

    Composite Matrix Transformation - Reflection

    Homework Statement Let T1 be the reflection about the line 2x–5y=0 and T2 be the reflection about the line –4x+3y=0 in the euclidean plane. (i) The standard matrix of T1 o T2 is: ? Thus T1 o T2 is a counterclockwise rotation about the origin by an angle of _ radians? (ii) The...
  39. A

    A question about the polarization due to reflection

    it is known that light reflected at the Brewster angle is plane polarized. This is due to during an oscillation of charge, no transverse wave is generated in the direction of oscillation, and the amplitude is maximum for wave propagating perpendicular to the direction of oscillation. But i came...
  40. V

    Reflection with a complex material

    Hey I am currently looking into refractometry, and how light reflects off a interface between to materials. I have looked through most of the other threads but nothing really explained what I am looking for. My problem, I have a digital refractometer and I am measuring the reflective angle...
  41. M

    Reflection of Light: Exploring Electron Behavior

    As I understand that the electrons absorb the radiation and then re-radiate a part (or color) towards the incoming radiation is called reflection. However, if the frequency of radiation absorbed and re-radiated is dependent on the electron state, how does a faithful reflection of all visible...
  42. K

    Exploring the Laws of Reflection

    I am trying to understand the laws of reflection better. I know that if a large flat mirror is placed on one wall of a room that the room appears larger than it actually is, but by how much? Is it exactly twice as big? Also, How does the size of the image that is reflected from a plane...
  43. Cyrus

    History Making History Today - A Reflection

    I just helped make history today......wow. Did anyone notice the McCain people Booo every time he mentioned Obama. But the Obama people clapped for McCain out of respect. I though both had amazing speeches. Finally, America is back on track. Its long over due. I look forward to my...
  44. D

    Bragg Reflection = Standing Waves

    Homework Statement I've got my exam in solid state physics tomorrow, and although I've understood most of the most complex subjects now, I feel I'm missing the understanding on one fundamental phenomena; Bragg reflection.. Throughout Kittel it's mentioned, that when we're at the first...
  45. H

    Laser Reflection: Why Does it Appear Speckled?

    When laser light is reflected from a diffuse surface, what is the reason that it appears speckled?
  46. F

    QM binding energy and reflection coefficient

    Homework Statement consider a potential given by V(x) = infinity x < 0 = 0 x > a = a negative function of x in between suppose it is known that the interior wave function is such that (1/u) (du/dx) at x=a = f(E) a. what is the binding energy of a...
  47. H

    Solving Electron Acceleration and Reflection Problems

    Homework Statement Electrons are accelerated from rest by a voltage of 59.0 V. After that acceleration: 1.What is their speed? 2.What is their De Broglie wavelength? 3.The accelerated electrons are then reflected by a crystal with crystal spacing d of 0.085 nm. Through which angle are...
  48. H

    Phase Change of \pi: Exploring Reflection and Non-Reflective Coatings

    Hi, When exactly does the phase change of \pi occur when a EM wave reflects from a surface? I notice that it happens in Lloyd's mirror for example, and also when considering non reflective coatings on lenses. Is it just when the EM wave is going into a medium with higher refractive index or...
  49. S

    Reflection and Refraction (Lateral Displacement)

    1. The Problem A thin beam of white light is directed at an angle α = 36.4° with respect to the horizontal, onto the top of a square block of silicate flint glass near its top corner. The perpendicular length of the block (or height is 1cm). The block’s refractive index n is 1.66 for blue...
  50. M

    Reflection of light off film, wavelength and thickness?

    What is the thinnest film of MgF2 (n = 1.39) on glass that produces a strong reflection for light with a wavelength of 680 nm? This is the exact question I am faced with. I didn't really know where to begin so I tried using the ratio of n-air/wavelength to n-film/(new wavelength) to try and...
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