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. J

    .Comparing Wave Reflection in Strings and Wires

    Hi I have a question about pulses in a wire. If I have a single wire of length X and I send a pulse through the wire, when the pulse gets to the end of the wire, does it reflect back with the opposite phase or in phase when the original pulse? I'm trying to visually compare the behavior with...
  2. C

    Sound wave reflection question

    Hello, I am working on a problem, how would the echoes from a large and small insect compare if they were the same distance from a bat? (from the bats point of view of course) I don't think they would differ at all. If the insects are not moving, then there would be no differance. The only...
  3. K

    What is the correct formula for calculating focal length in convex mirrors?

    I'm studying for a test that is going to cover mirrors and lenses. I was under the impression that the focal length for any concave or convex mirror was half the radius of curvature: f=r/2 but one of the questions in my book involving a convex mirror uses a different value for f, according...
  4. P

    Proving the Reflection of Light Ray from Parabolic Mirror on x-Axis

    I'm hopelessly stuck on this question. Any help will be greatly appreciated. Prove that if we have a parabolic mirror with focus at F and axis of symmetry the x-axis, then a light ray emmited from F will be reflected parallel to the x-axis. To prove this consider the parabola y^2=4px (where...
  5. P

    Interference using a reflection grating: how to determine the slit width?

    Hello! I'm working on a surface analysis of a silicon-microstrip-detector. That is basically a silicon wafer with p- and n- doped strips on it. They are periodically produced on the crystal. Therefore I can use it as a diffraction grating for visible light to do my surface analysis. My light...
  6. N

    Solving the Biconcave Lens Problem with Reflection and Refraction

    Here's the problem: Here's what I understand: I know what a biconcave lens looks like, and how it behaves (for the most part). Of course I know that the index of refraction is ~1.00. And since the radii are equal that makes the equation somewhat easier. The thick lens equation is...
  7. K

    Physical meaning of reflection

    Hello all, I was wondering about the physical meaning of reflection for quite a while. Suppose say I have a transmission line and say it has reflection at discontinuity what does this mean in physical sense. It would be really helpful if I get answers for this. I have couple of other...
  8. N

    Angle of incidence and reflection of a parabola?

    I've been playing around with parabolic mirror calculations in my free time, and right now I'm trying to derive the equation for the line that models the angle of reflection off of a point. I understand how to find the angle of incidence and that the reflection will have the same angle off the...
  9. P

    Linear Algebra reflection question

    Hi this is my first post here. So be nice now o:) I´ve have a problem with a question: T:\mathbb{R}^2\rightarrow\mathbb{R}^2 first reflects points through the vertical x2-axis and then rotates points \pi/2 radians./Perrry
  10. S

    Reflection of a High-Energy Particle at a Potential Barrier

    Consider a particle moving in 1 dimension and encounters a potential step. Suppose that the total energy of the particle is higher than the potential barrier height, E > V. Wouldn't a classical mechanical particle, traveling at velocity v, break through the barrier? And wouldn't a quantum...
  11. Z

    Reflecting of reflection in relation to time

    I'm speculating about the nature of time, or at least a perception of it, and I'm thinking of an analogy to represent some of these speculations. I thought about how images are reflected to infinity when placed between two mirrors, but I would like to specifically know what the reflection of...
  12. H

    NaCl Crystal Reflection: Determining Wavelength & Sinus

    The distance between the primary planes of a NaCl crystal is 2.82 Å. It was found that the first order Bragg reflection of a monochromatic x-ray beam occurs at sinus= 10 degree. (i) Determine the wavelength of the x-ray. (ii) Determine the angle, sinus for a second order reflection.
  13. S

    What Is the Minimum Height of a Rear-View Mirror to See the Entire Rear Window?

    I have been trying to solve this problem using many equations, but am not getting the right answer. I guess I'm not using the right formula because I don't know it. Can someone please help. The rear window in a car is approximately a rectangle, 1.17 m wide and 0.160 m high. The inside...
  14. Amith2006

    Change in amplitude of wave on reflection

    Sir, When a wave is reflected from a free end or a rigid end, will there be a change in amplitude always?
  15. P

    Partial Reflection: Explaining Glass & Thickness Effects

    Was recently re-reading QED and wondered whether there was any "simple" explination of partial reflection? How does the thickness of glass affect reflection if it's a particle?
  16. R

    Transparency, Reflection, & EM Rays: Exploring Physical Properties

    What is the factor that determines whether an object will be transparent, translucent, or opaque? Also, what makes reflecting surfaces reflect EM rays?
  17. cepheid

    Why Doesn't Incident Light Interfere with Reflected Light in a Mirror?

    Say that light is incident on a plane mirror, normal to the surface (i.e. zero degrees from the normal). Why does the reflected light (which heads back toward the source) not interfere with the incident light?
  18. M

    Realizing My Unknowing Insensitivity: A Reflection

    So, I just found out that a nickname I used to refer to my little sister by (and still occasionally do) is an ethnic slur for Hispanic people. I won't say what it is, except that it has to do with beans. In case you're wondering, the name was a corruption of the name of one of the characters...
  19. B

    Polarization Reflection question

    A thin film of ethyl alcohol (n=1.36) is spread on a flat glass plate and illuminated with white light. When illuminated and viewed from directly above, it shows a coloured pattern in reflection. If the only visible light reflected by a certain region of the film is yellow (lambda=560nm), how...
  20. O

    Why Do Some Photons Get Reflected While Others Are Absorbed?

    How do an atom "know" when to absorb a photon, and when not to? It seems like an atom absorbs all photons that either has energy that corresponds to the difference between two energylevels, or has any type of energy at all in which case the photon energy helps speed up the atoms oscillations...
  21. Y

    Light: Wave or Particle? - Reflection

    I know this has been discussed to death and I acknowledge the fact that there truly is no conclusive answer. However, I have to do my best to outline that light is indeed a particle through its properties of reflection. So far, I've simply come up with the fact that laws of reflection follows...
  22. K

    Why isn't radio wave reflection in the ionosphere direct?

    Hi, why the reflection in ionosphere isn't direct?,
  23. T

    Visible Light Reflection from Oil-Water Interface in Parking Lot

    A tiny layer of oil (n = 1.25) is situated on top of a water puddle (n = 1.33) in a parking lot. If the thickness of the oil is 242 nm, the what color(s) of visible light will give a strong reflection? 2t=m*lambda/n2 2t=242nm/1.25 and then 2t=242nm/1.33 i just don't know what goes where...
  24. D

    Understanding Phase Shift Upon Reflection: A Closer Look at Fresnel's Equations

    Let's say I have light at normal incidence. Under what circumstances is there a phase shift? Under what circumstances is there no phase shift? My best guess is that there is normally a phase shift of 180 degrees. The exception is when n_incident > n_reflected, but I don't really know. To...
  25. T

    Total internal reflection questions

    hey so I'm doing this question on total internal reflection and have got myself totally lost here is the question: what is the smallest angle \theta(1) for which a laser beam will undergo TIR on the hypotenus of this glass prism? after reflecting off the hypotenuse at \theta(c) the...
  26. R

    [optics] reflection and refraction

    i have a problem with understanding the phenomenon of reflection and refraction of light. when considering light as a electromagnetic wave i cannot imagine how it can be reflected or refracted when meeting a surface of different refractive index. it just sounds illogical to me that sth...
  27. A

    Reflection of sound from open pipe

    We know that when there is a change in medium there is reflection of sound.when it passsess through a pipe open at both end's , sound reflects.Actually the medium is same inside the pipe and outside the pipe, then how can we explain the reflection of sound from other end of pipe?
  28. I

    Light Reflection Through Mirrors

    What are the ways that things can be reflected through flat, converging, and diverging mirrors? I know that for flat mirrors it's a virtual image equal to the size of the object For the converging mirror, if the object is placed farther than the radius of the mirror, the image is real and...
  29. B

    % Reflection vs Wavelength Chart. Any?

    Does anyone have a link to a chart or table that shows the % of light reflection from some solid as the wavelength is changed from RadioWave to X-ray?
  30. E

    Mirror Height for Self-Reflection at Distance D for H

    Hello, I was wondering how to find the minimum height of a mirror so somebody of height H that is at a distance D of the mirror sees himself from head to toes. Anybody can help me out ? Thanks !
  31. D

    I AM staring at a reflection of myself.

    That's IT. And by that I means THIS.
  32. P

    Exploring Reflection of Light: What is the Path of an Individual Photon?

    I have been reading Feynmanns 'QED' and am trying to understand what happens when light is reflected from a surface. I would be grateful if someone could answer the following question. I am not sure which of these views (if any) is correct. 1) When light is reflected from a surface a photon...
  33. D

    Antenna Signals: Reflection, Distance and Phase

    Hi let's suppore that an antenna creates two signals... The two signal are received from an other antenna but with a main difference. The one of the two signal is reflected in a surface which means that it will travel bigger distance... The two signals are received with a difference in the...
  34. L

    Light's reflection - wats ur perception?

    hi all one basic question in physics aroused owing to my poor memory. i vaguely remember that there is a difference in the colour of the object we see in reality and that generated by a television or for that matter any artificial source of light. 1) Now how does our eye perceive these (...
  35. P

    What is the loss percentage of standard glass mirrors in multiple reflections?

    I have two mirrors at the same height on opposite walls facing each other in my bathroom. I took a laser pointer and put it in between the mirrors and directed the beam at one, such to where the reflected beam hit the other mirror, and back on the first and so on. Anyway, I noticed probably 16...
  36. -Job-

    Reflection at the Quantum Level

    If i throw a tennis ball against a wall in a 45 degree angle, it reflects with a 45 degree angle. A beam of light against a mirror also reflects in a 45 degree angle. If i throw a tennis ball against some irregular surface in a 45 degree angle then the ball, depending on the shape of the...
  37. P

    2 internal reflection questions

    One of my problems reads, 1. Determine the maximum angle for which the light rays incident on the end of the pipe in Figure P35.38 are subject to total internal reflection along the walls of the pipe. Assume that the pipe has an index of refraction of 1.40 and the outside medium is air...
  38. P

    How Do You Determine Image Location and Type Using a Spherical Mirror Equation?

    If you place an object a distance so from a spherical mirror, how do you calculate the image location given that the image is right side up and magnified by two times? I know the equation but I always get confused about what signs to use for lenses vs. mirrors, etc. I know the magnification...
  39. J

    Law of reflection and refraction

    Hi; I was wondering if someone could please help me with this question: "When you measure the law of reflection and the law of refraction, what is the advantage of making 2 measurements: one clockwise from the normal and one counterclockwise from the normal?" Could an advantage be that this is...
  40. T

    Parabolic Reflection: Perfect Virtual Image with Realistic Focal Length?

    In owning more than a few Newtonian telescopes in my life, I have just a little knowledge concerning parabolic mirrors. But I could use the help of experts in the field... I was wondering if a larger parabolic mirror could reflect a perfect, aberration-free virtual image, of a nearby object. For...
  41. M

    Melt a Perfect Mirror: Atomic Mechanisms of Reflection

    Is it possible to melt a perfect mirror by radiative means? (reflects light of all frequencies with no absorption) Which leads me to ask. What is the mechanism (at the atomic level), for the reflection of light? I've never had a satisfactory answer on the mechanism of reflection. Is it...
  42. S

    Fetal Heart Wall Velocity from Ultrasound Reflection

    A sound wave travels at a frequency 2.25 MHz through a pregnant woman's abdomen and is reflected from the fetal heart wall of her unborn baby. The heart wall is moving toward the sound receiver as the heart beats. The reflected sound is then mixed with the transmitted sound, and 87.0 beats per...
  43. T

    Mirror Reflection: Left-Right Exchange Explained

    Why is it that a mirror reflection only exchange the notion of left-right but not up-down ? I mean if I were to stand in front of a mirror, my mirror image exchanges my left hand with the left, but not my head with my legs.
  44. B

    What Is the Line of Reflection for the Matrix Transformation f(v)?

    f(v) = (the matrix) |cosx sinx | |sinx -cosx |(v) If x is in R and f: R^2 --> R^2 show that f is a reflection in a line L through the origin, and find the line of reflection. im having trouble figureing this out, i know that i need to find a line L fixed by f, and then to...
  45. wolram

    The Intelligence of a Spacetime Mind: A Reflection

    What is your iq, 120, 130, 140, huh ,well that's nothing, i am so intelligent my mind fills all of spacetime, is it any wonder then that i seem a little dim locally with a mind spread so thin.
  46. P

    Experimental Set-up for EMISSION & REFLECTION Spectroscopy: Is it Easy?

    Hi, I went to my proff to ask for my master thesis, he told me that you yourself have to do the experimental set-up for EMISSION AND REFLECTION SPECTROSCOPY ,,,but I am not that experienxed, anybody knows is it an easy task or...?
  47. Reshma

    What Causes Total Internal Reflection?

    Can someone explain the phenomenon of total internal reflection?
  48. C

    What is DLP™ technology and how is it used in various products?

    Does someone know a device that can reflect a laser beam in order to project an image? I remember years ago I saw a microchip that had an array of small mirrors, and was able to modify the angle of those mirrors... I think it was from Texas Instruments.
  49. wolram

    Essentials We Can't Live Without: A Reflection

    So what thing(s) would you be lost without, or couldn't give up?
  50. J

    Doppler effect: Moving source with reflection

    Suppose a sound source S is moving towards a stationary wall and that a listener L1 is moving with the sound source. Describe in a few lines why the reflected sound heard by the listener L1 is Doppler-shifted by about twice the amount that a second listener L2 would hear standing by the wall...
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