Reflection Definition and 959 Threads

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. Malvina

    I Why does the phase of the reflected wave from a denser medium change?

    Why does the phase of the reflected wave from a denser medium change?
  2. M

    Reflection probability in Quantum Mechanics

    For this, The solution is I have doubt where they got the reflection probability formula from. Someone may know how to find it. I think that ##R + T = 1##. But I'm not sure where the transmission probability formula comes from either. Kind wishes
  3. hraghav

    Find the location of the diver's reflection in the convex mirror

    Dapparent = Dreal / n Dapparent = 181.2 / 1.54 = 117.66 cm the total distance from the mirror to the diver is: do = 193 cm + 117.66 cm = 310.66 cm As the object is in front of the convex mirror, do = -310.66 cm f = -R/2 = -222.4 / 2 = -111.2 cm 1 / f = 1 / do + 1/di 1 / -111.2 = 1 / -310.66 +...
  4. T

    A Ansys FDTD simulation for phase change due to reflection

    Hello, I am currently simulating phase change due to reflection on gold (Au) using Ansys FDTD. My setup includes using a Frequency Domain Field and a Power monitor to observe the angle of the E-field in x-polarization. However, the phase change tendencies I'm observing do not match those in my...
  5. X

    I How Can I Build an Effective DIY Helmet-Mounted HUD?

    Hello, I'm trying to build a helmet-mounted display. Basically a HUD that is contained fully within a helmet. I am not experienced with optics though and can only sift through what the internet has to offer. I don't want it to be a "put your phone down next to an angled piece of polycarbonate"...
  6. A

    Is the Solution for Rotation of Spherical Mirrors Incorrect?

    I think the given solution is wrong. The lens forms image at ##(+75,0)## which is ##25 cm## from pole of the convex mirror which acts as virtual object for mirror. It is true that the reflected ray is rotated by ##2\theta## as in case of plane mirror. Rotation of Spherical Mirrors But that...
  7. P

    Please explain this mirror

    The following photo was taken of a mirror in my hotel room in Dublin, Ireland a month ago. This mirror has two individual panes, I assume silvered differently. Why? Is the magnification of the left pane intentional, a mounting effect or a consequence? I appreciate whatever you may have to...
  8. A

    B How would someone see light from something like a flashlight in a tunnel?

    What I mean is that how would someone see light from something like a flashlight in a tunnel? The idea of light rebounding like a ball against a wall I do understand. What I would like to apply this to is graphics programming. the objects that I would simulate this for are puddles on the floor...
  9. elou

    B Light beams and their reflection

    I must add, that, when used in a lit space, or in daylight, spraying before the mirror does not make any light rays visible. Is it simply a matter of light scattering? Also, I am not sure whether this question belongs here or in classical physics.
  10. E

    I Why Are Reflected Rays Often Ignored in Lens Studies?

    Hi, I am wondering why reflected rays are not considered with lenses? If a Ray strikes a surface another is reflected off that striking point; however, this is not added when studying lenses, only refracted rays are considered. Is there any law which gives the ratio of reflected and refracted...
  11. xphrnzrjh

    Refractive index of seawater and a diver transmitting RF for 100 meters

    I thought I maybe need to find a way to calculate the refractive index (n) and using that calculating the velocity and then the time but I haven't managed to figure out how to get the refractive index? Would love your help.
  12. Hak

    Mirror system in geometrical optics

    I tried solving it in this way, distinguishing 3 cases and passing the first ray through the point located at a greater distance from the vertex of the angle formed by the two mirrors: 1) the angle of incidence of the ray on the mirror inclined 45° to the horizontal is 45° or 0°: in the first...
  13. M

    B When Would Planets Go Dark if the Sun Went Out?

    If the Sunlight lets say would go off, exactly how long would astronomers on Earth still see sunlight reflected on the surface of Mercury, Venus, Mars, the asteroids, Jupiter Saturn, etc.? I mean Sun goes dark at 0:00 from the point of view of Earth-based observers. At that exact moment, if...
  14. B

    B Mapping wave forms to sphere, does wave form y=0 have a reflection?

    Zero does not have an inverse. And y=0 does not have an inverse. Does the wave form y=0 for all x have an inverse?
  15. I

    I Mirror rotates any polarisation by 90°?

    Over each eye is a linear polariser and they are orthogonal to each other. So I conclude from the experiment that the polarisation must have been rotated by 90° by the mirror. That reminded my of phase plates but they only work because their refractive indix depends on the angle. Along two...
  16. A

    Air wedge - why is reflection from top of first slide ignored?

    My textbook derives the condition for bright and dark fringes on an air wedge by assuming that the reflected and refracted rays have a path difference of pi. Hence the conditions for bright and dark fringes end up being the opposite of what is expected. However I did not really understand the...
  17. Ahmed1029

    I Reflection, refraction, and Snell's law

    Where do the laws of reflection, refraction, and Snell's law come from in geometric optics? Are they derivable from basic laws of physics?
  18. OliverFroelich

    A Iphone Reflection has a pattern

    Hi all! I'm sitting in the office on what would normally be a dive day so I'm slightly over observant. The sun is coming in heavy through my window, and holding my iPhone I began playing with the reflection on my office wall it produced. The reflection at first was no different then any light...
  19. hagopbul

    I have a question about the mathematical model of a reflective curve

    Hello : Have a question regarding the mathematical model of reflective curve where could i find information on it ? (pdf , webpages , ebooks ,...etc ) Other than Wikipedia Best Regards HB
  20. A

    B Space, Reflection: See Earth's Past in Mirror?

    can you theoretically put a mirror in space, take a photo of earth/dirts reflection and see it in the past?
  21. nmsurobert

    B Letter reflection from beer can

  22. O

    B Parallel light reflection for a one-way speed of light measurement setup

    Hello, Is there a mirror that will reflect light in parallel trajectories ? If yes, is the reflected light in sync, and will all beams hit a flat surface simultaneously ? Thank you
  23. Dom Tesilbirth

    The magnetic phase change of an electromagnetic wave during reflection

    If the question had mentioned ##\overrightarrow{E}## instead of ##E_\bot##, then we could have used ##\overrightarrow{B}=\dfrac{1}{v}\widehat{k}\times \overrightarrow{E}## to get the direction of the magnetic field. But the question had only mentioned ##E_\bot##. To my understanding, knowing...
  24. wnvl2

    I Reichenbach Synchronisation: Proving i=r

    I use Reichenbach synchronisation. The one-way speed of light (OWSOL) in the x and y-direction is ##\frac{c}{2\epsilon}## and in the reverse direction it is for both ##\frac{c}{2(1-\epsilon)}## such that the average round trip speed of light is ##c##. For any choice of ##\epsilon## the physical...
  25. V

    Reflection of sound wave in an open organ pipe

    I know that standing waves form in an open organ pipe. Since, standing waves can only form from superposition of original wave and reflected wave, so there must be a reflected wave in an open organ pipe. But I fail to understand how sound wave can reflect at the open end of organ pipe.
  26. Aaronazi

    A Reflection Instant? Atomic Level Causes Explored

    What causes reflection on the atomic level? I believe that the interactions of light and the electrons of a body take at least very very small amount of time. The time is probably negligible but does that time even exist or does the reflection instantly happen.
  27. kuruman

    B Why do reflections in water sometimes appear different from what we see?

    For quite some time I was under the mistaken impression that the specular reflection of objects from the calm surface of still water forms an image that is the same as the image I see except it's upside down. That is not the case. In the picture below* I have circled in white a couple of...
  28. W

    I The reflection of the sunset on the water is redder--Why?

    I presume that some kind of absorption occurs when the sunset is reflected on the water, but can anyone describe this in more detail?
  29. M

    I Interference by reflection on a CD

    A fairly focused beam of light incident on a CD projects a clearly visible interference pattern onto a screen. May I infer that it has good (or at least enough) spatial coherence? This property is evident, for example, in a lens-focused beam of light produced by a LED or by a ray of sunlight...
  30. R

    How Does Mathematical Theory Explain Multiple Wave Reflections?

    I know for a wave moving from left to right, ##\psi_i = Ae^{i(\omega t - k_1x)}## The first reflection where ##Z_1## is ## R_{12}Ae^{i(\omega t - k_1x)}## The second reflection. The wave moves from 2 to the limit between 2 and 3 then reflect... Thus, ##T_{12}R_{23}T_{21} Ae^{i(\omega t - k_1 x...
  31. P

    Analogy between EM wave reflection and S-parameters

    It is well known that one can solve incident an reflective wave in homogeneous linear media by matching PDE boundary conditions. In the electrical engineering community, one solves similar problem using smith chart and scattering parameters for 1-dimensional propapation of TEM modes in...
  32. Vin B

    Simulate mach reflection with mach stem generation using Ansys Fluent

    I need to simulate mach reflection with mach stem generation using on Ansys Fluent. The wedge angle is of 22deg at Mach 5.
  33. baby_1

    Complex Reflection and Transmission Coefficient in oblique incidence

    Hello, Something has made me confused after studying the Snell equations these days. Regarding the Balanis Advanced engineering electromagnetic( the pages have been attached), and based on that the reflection and transmission coefficient can be complex I need to rewrite the (5-23a) again...
  34. E

    Angle of incidence and total internal reflection

    the angle of incidence at A is 40°, then why did the answer key say "angle of incidence at A is just less than 90°". it is obvious that 40° is quite far from 90° right?
  35. Mr_Allod

    Reflection and Refraction in an Elliptical Imaging Mirror

    My thoughts so far: a. Since the critical angle occurs at the origin for the given parameters I would imagine that the maximum power reflected would be 100% since at the critical angle ##\theta_t = \frac \pi 2## and ##r_ {\perp} = r_{\parallel} = 1##. I do not know how I might go about finding...
  36. J

    Fish Reflection: Analyzing Light's Interactions with Water

    So first I looked at where the image of the fish appeared to be when it went through the water surface. since we can assume the water is flat, R is infinity, so n1/p=-n2/q. plugging in the values (n1=1.29, n2=1, p=3.5) I get q=-0.3686. So the image of the fish appears at 0.369 above the...
  37. L

    A potential well with 3-fold reflection symmetry

    When we are talking about Bloch's theorem and also the tight-binding approximation, we can use them to help finding eigenstates of a system. However, I am so confused how to apply it in this case (below is my homework) and don't even know how to start it... All I understand about the Bloch's...
  38. B

    Double Glazed Window Reflection

    I hope this is not a stupid question but I attach a photo of a reflection of a square double glazed window showing on a wall opposite the window. Could someone please explain to me what is happening here. I presume the outer circular reflection is showing the extent of the suns rays and the...
  39. P

    Prove the reflection and transmission coefficients always sum to 1

    Consider polarized light crossing a sharp boundary between two volumes, each of a different but uniform refraction index ##n_1## or ##n_2##. Prove that the sum of the transmission and reflection coefficients of this light ##R+T=1##, where $$R \equiv {I_R \over I_I} = \left( {E_{0_R} \over...
  40. EnergyInMotion

    Reflection of Radio Waves by a Mirror-like surface

    Hey guys, I'm new to the physicsforums. I wanted to share some videos I made and see if anyone was interested or wanted to discuss what they see. In this video I show in a manner in which is VERY easy to see, that a reflective surface will reflect not just light but also radio waves (and most...
  41. R

    Deriving the Law of Reflection from Huygens Principle

    Attached is section 33.7 from my book, which introduces Huygen's principle in order to derive the law of reflection. I am more used to the ray model rather than the wave model, so I'm constantly going to try to relate everything back to rays. Making this connection also helps with completeness...
  42. P

    Questioning My Thinking: A Reflection

    I started to do this, but I'm not sure my thinking is good.
  43. Mr_Allod

    EM Wave Reflection and Transmission Between 3 Materials

    Hello there. I set up the problem like this, I have a wave incident from air on the anti-reflective coating consisting of: ##\tilde {\vec E_I} (z,t) = \tilde E_{0_I} e^{i(k_1z- \omega t)} \hat x## ##\tilde {\vec B_I} (z,t) = \frac 1 v \tilde E_{0_I} e^{i(k_1z- \omega t)} \hat y## This wave gets...
  44. Vivek98phyboy

    Reflection of inverted waves to form a standing wave

    Standing waves in a string fixed at one end is formed by incoming and reflected waves. If reflected waves are 180° out of phase with incoming wave, how could they combine to give an oscillating wave? Shouldn't it be completely destructive interference all the time across the whole length of string?
  45. Vivek98phyboy

    Contradiction in Phase of reflected sound

    While studying the fundamentals of sound waves in organ pipe, I noted that the fact about phase of reflected waves is contradicting while referring multiple sources This book of mine describes the reflection from a rigid surface/closed end to be in phase Whereas this one describes the...
  46. J

    Frequency and Sound Wave Reflection

    I got that the sound wave will take 0.3s between the student and the left wall. It takes 0.5s between the student and the right wall. The first time these waves will coincide is 1.5s (5 trips for left side and 3 for right side). I then did 1/1.5 to get 0.67Hz. However, the answer is 6.67Hz. I'm...
  47. F

    Angle of reflection of a beam light on a moving mirror

    Before to open this topic, I found this there. It's quite similar, if not the same, but I'm a little confused, so I'm here. The situation is represented in this image. From optical geometry, ##\theta_{incident} = \theta_{reflected}## The four-momentum in ##S'## is the following one...
  48. M

    Engineering Voltage pulse sketches for reflection on a lossless transmission line

    Hi, I was recently attempting a question about transmission lines and I don't seem to really understand how the voltages travel through the line. Question: If we send a voltage pulse of amplitude ## V_0 ## through a lossless transmission line, what does the voltage at the output look like when...
  49. LCSphysicist

    Is Reflection of an Incident Wave Lagging or Advancing?

    Actually, maybe i am confusing something, or valuing unnecessary things, but this doubt arises and i am not sure how answer it. The reflection of an incident wave changes (suppose it will change, we don't need to talk when or why to go on the discussion) by π rad, but, this reflection lags the...
  50. faiello

    Radar Reflection: Charged vs Non-Charged Objects

    A question I’ve been trying to figure out for the last 5 years with a friend of mine: Would the radar reflection from an object be different if the object is charged or not charged?
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