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

    News With the passing of Pope John Paul ll, perhaps some reflection on

    With the passing of Pope John Paul ll, perhaps some reflection on religious beliefs is appropriate. Religion is defined as a set of beliefs concerned with explaining the origins and purposes of the universe, usually involving belief in a supernatural creator and offering guidance in ethics and...
  2. S

    How Do You Calculate Lateral Displacement in Refraction Problems?

    Hello! I'm having difficulty solving this problem, I was wondering if you can help me solve it. Light is incident in air at an angle on the upper surface of a transparent plate, the surfaces of the plate being plane and parallel to each other. A ray of light is incident at an angle of 66.0...
  3. marlon

    Why Does Reflected Light Experience a Phase Change?

    Reflected light will experience a 180 degree phase change when it reflects from a medium of higher index of refraction and no phase change when it reflects from a medium of smaller index. This is very well known. However i am wondering why that is ? Can anyone give me some calculations that...
  4. J

    Calculating Height of Cliff Using Reflection Interference of Radio Waves

    Radio waves of wavelength 250 meters from a star reach a radio telescope by two separate paths. One is a direct path to the receiver which is situated on the edge of a cliff by the ocean. The second is by reflection off the water. The first minimum of destructive interference occurs when the...
  5. G

    Internal Reflection and Maximum Angles

    A corner reflector is to be made from a triangular prism with index of refraction n=2.56, as shown in the diagram on your assignment. What is the maximum angle (in °), with respect to the normal to the front surface of the prism, (theta), such that total reflection will occur? Ok this must be...
  6. P

    Why is there total internal reflection

    Why will total internal reflection occur when angle of incidence is greater than the critical angle? Anything deal with the particles?
  7. Crumbles

    Specular Reflection from a Reflection Diffraction Grating

    I understand that a laser beam shining onto a diffraction grating produces a 0th order, 1st order etc... diffracted beam. My question is: What is the wavelength of the specular reflection [0th order beam] off the grating in regards to the wavelength of the incident beam?
  8. F

    How Does Rotating a Plane Mirror Affect the Angle of Light Deflection?

    Prove mathematically that when a plane mirror is rotated an angle theta about an axis through its center, the angle of deflection of a light is equal to 2theta. How am i to show draw this out? I have already drawn my points and lined up my angles with and without the mirror rotated. I don't know...
  9. B

    Does specular reflection impart a force?

    I am currently doing a PhD on the subject of solar sailing (if you don't know what that is and are curious enough, a quick google search on "Solar sailing" will give you a plethora of websites that will explain it for you). Solar sails depend crucially on forces generated when a photon is...
  10. S

    Reflection Intensity: Iron vs. Hollow Black Box

    If monochromatic light of the same amplitude is shown on a closed hollow black box and a closed black box filled with iron, will there be a difference in the intensity of light that is reflected back due to differences in the absorption of light in the two boxes?
  11. M

    Simple reflection thought experiment

    I am going to start out with a simple thought experiment: A particle is moving towards a wall at a 90 degree angle. The wall is perfectly smooth; therefore, when the particle bounces off, it will be traveling along the same path as it did when it came in. Does the ball ever come to a...
  12. T

    Help in sound question and reflection question

    hello :uhh: i have these questions that i don't know how or what to do :uhh: :confused: Matt drops a water balloon from a balcony 15m up. As it falls, someone calls out 2.0 s after release to warn the bystanders below. If the air temperature is 20 C and the people can move instantly...
  13. K

    Reflection in Mirrors AAARRRGHHHH

    Reflection in Mirrors! AAARRRGHHHH >> How many times will the incident beam be reflected by each of two parallel mirrors that are 1.60m high and 1.40m apart? The beam is aimed at the left mirror at 5 degrees from the horizontal. Okay I am completely lost here. I've read over all my...
  14. S

    Solving a Hallway Reflection Problem

    I am struggling with the following problem. I believe it shouldn't be hard - i must be missing something :confused: ? A tuning fork generates sound waves with a frequency of 246 Hz. The waves travel in opposite directions along a hallway, are reflected by end walls, and return. The...
  15. O

    Problem figuring out the reflection of a pulse on a rope

    I have problem figuring out the reflection of a pulse on a rope with a fixed point. Do you know some websites to find animations about it?
  16. DaveC426913

    Unlock the Mystery of Taking a Reflection Photo in Your Own Backyard

    This is a 'How did I do this?' teaser. A couple of notes first: - The picture I include is simulated (Googled for a generic shot). Sorry, best I could do without the original. Ignore the fact that a] it's not me, and b] that the pic is indoors. - Even though this is a simulation, I actually...
  17. V

    A Room of Infinite Reflection: How Bright Will It Get?

    What if you are in a room and the walls, floor and ceiling are all perfect reflectors, and there's a light on in the middle of the room. How bright will it get in there?
  18. R

    How Does the River Allegory Reflect Our Life's Journey?

    I once had a co-worker and close friend, who was a 2nd degree black belt in Sho en ru (sp?) Karate and had his own dojo. He was practicing, teaching and of course learning a form of Zen meditation. He told that the way he looked at it was that we were all travelers on the same river. Some of us...
  19. H

    Solve AP Physics Problem: Reflection & Refraction at a Boundary

    AP PHYSICS PROBLEM...i forgot the formula, someone help me solve! This won't take lon Light of frequency 6.0 x 1014 hz strikes a glass/air boundary at an angle of incidence, ø1. The ray is partially reflected and partially refracted at the boundary as shown. The indices are shown. (a)...
  20. M

    Faster than Light? Exploring X-Ray Reflection

    Faster than c! hi I read that the refractive index(n) for X-rays in meterials are less than 1(very little less than 1). I got confused ..I am using X-ray reflection at the moment. But I am not convinced by the fact that n<1 means faster than c(velocity of light in vacuum or in air)! hope...
  21. P

    Help Solve Physics Problem: Reflection Question

    Need some help on a practice physics problem. You need to place a mirror on the left wall, so that the reflected light from the bulb exactly fills the right wall. ceiling _________________________ | | |...
  22. A

    How can I determine the velocity of the ionosphere based on wave reflections?

    Hello! I am having a problem with this problem about the reflection of a "radio wave" in the high atmosphere. (ionosphere) "A short-length wave receiver receive two signals from a distant source at 500Km, beeing those signals, one from the normal conduction through the atmosphere and the...
  23. K

    Light Reflection at a Point: Exploring Possible Answers

    imagine that i have a pair of LEDs throwing light on the same point on a piece of paper. This is possible if the LEDs are inclined equally at an angle to the normal coming out of paper, right? now if i consider two rays hitting the paper at the same point, then where can i explain the...
  24. K

    Exploring the Reflection of Light on a Piece of Paper

    imagine that i have a pair of LEDs throwing light on the same point on a piece of paper. This is possible if the LEDs are inclined equally at an angle to the normal coming out of paper, right? now if i consider two rays hitting the paper at the same point, then where can i explain the...
  25. F

    Total Internal Reflection Confusion

    Hi, I'm new here... I already read about how the signals are transmited through the fibre optical cables... total internal reflection But what I don't understand is the another day I was scribbling it on a piece of paper (the total internal reflection that is)... I noticed that from the way...
  26. D

    Reflection or not with two layers with different indices of refraction

    The packet doesn't explain this concept very well, and the book doesn't seem to explain it at all. A glass surface (n = 1.5) is coated with a film with an index of refraction n=1.3. If light of frequency 6x10^14 cps is incident almost normally on the film, find the minimum thickness that...
  27. N

    What is the meaning of N in wave optics of reflection?

    Hi, Right now I am solving some exercises in connection with wave optics. If we have three layers of different materials (ex. air, gasoline, water) and we send a light ray through these layers and we calculate the wave length of the reflected rays, then we use these formulas: D = N*l; (D =...
  28. C

    What is the Refractive Index for Total Internal Reflection in a 45-45-90 Prism?

    The Question: A 45-45-90 prism is immersed in water. What is the minimum index or fefraction the prism must have if it is to reflect totaly a ray incident normally on one of its faces. Now, we have found this question a bit hard to understand. We assume that light is hitting one of the...
  29. R

    What happens to a photon after it is detected?

    i have a somewhat elusive question (for me) about light. when you drop a bouncy ball, after it hits the ground, right before it bounces back up, its velocity is zero. correct? it becomes troubling when the ball is replaced with light. when light is reflected straight back to its source, it...
  30. M

    Solve Reflection Equation: Find Height of Shortest Mirror for Viewing Full Image

    I have a homework problem that I'm not sure how to figure out. What equation should I use for this? A person whose eyes are 1.8 m above the floor stands in front of a plane mirror. The top of her head is 0.12 m above her eyes. What is the height of the shortest mirror in which she can see...
  31. M

    Polarization of skylight, and polarization by reflection

    Can someone explain why skylight is polarized, and how polarization occurs through reflection? Thanks.
  32. E

    Need help with light reflection problems

    Need urgent help with light reflection problems Here are my problems: 1) A beam of light has a wavelength of 610 nm in vacuum. a: What is the speed of this light in a liquid whose index of refraction at this wavelength is 1.45? I used n=c/v to get 2.07x10^8 m/s. This is correct. b: What is...
  33. M

    What is the angle of reflection

    If a beam of light shines from the 10 on the face of a clock, reflects off a mirror in the center and strikes the 5, what is the angle of reflection. If anyone could help me, it would be much appreciated tyty.
  34. P

    Total internal reflection diagram

    ok, i need help with this one question. the diagram that goes with this question is at the following website: http://courseweb.edteched.uottawa.ca/phy1102A/Assignments/Problems/PHY1102A-Assignment%204_files/image005.jpg i tried attaching it but it was too big. ok so here it is: A ray of...
  35. Norman

    Solving Transfer Matrix for Total Internal Reflection

    Hello, I am trying to write the transfer matrix for surface with an s-polarized em wave incident on it. I want to look at the case of total internal reflection- but I don't know if it makes any sense to look at the transfer matrix in that case, since there is no transfer across the boundary...
  36. O

    Exploring the Tree of Self: A Reflection

    this is by no means polished. i will be working out my thoughts as i write. whenever i try to understand the concept of self, i visualize a tree. i am the tree but this physical me might only be a branch of the total me. the trunk is my core being(soul, spirit, etc?) and the big branches...
  37. M

    Investigating a Light Reflection Experiment

    I'm doing an response on a little experiment done in class. I'm having trouble understanding some parts. If someone could reply to the information below, it would really be appreciated. A large beaker is filled with water, it is covered on the outside by construction paper (any coulour you...
  38. A

    Does the human eye have limitations on detecting black surfaces?

    black surfaces apparently absorbs all light, that's why it appears black, but does it ever reflect light off its surface? what if its a polished black suface..we could actually see our own reflection on these surfaces.. so is there light being reflected at all? is there any difference from the...
  39. M

    Why does wood feel less hot than metal in the sun?

    A piece of wood lying in the sun absorbs more heat than a piece of shiny metal. Yet the wood fells less hot than the metal when you pick it up. Why?
  40. W

    Total internal reflection problem.

    If anyone could provide some insight into how I might go about solving this problem it would be greatly appreciated. Q: A ray enters the flat end of a long rectanglular block of glass that has refractive index n_2 as shown in the following figure. Show that all the entering rays can be...
  41. Dissident Dan

    Light: Reflection, Re-emission, or both?

    In basic science class, when talking about light and the colors of objects, people will say that the pigments absorb some light, but the light that represents the color you see is reflected. Is light actually reflected (the same photons/waves still exist and are now traveling in a different...
  42. denian

    Sound Reflection: Why a Barrier Must Be 10m+

    i read in the book. it stated that sound can be reflected by a barrier and the barrier must be large ( 10metre or more ). why?
  43. N

    How Does Light Behave at the Critical Angle in an Optical Fiber?

    The drawing shows an optical fiber that consists of a core made of flint glass (nflint = 1.667) surrounded by a cladding made of crown glass (ncrown = 1.523). A beam of light enters the fiber from air at an angle q 1 with respect to the normal. What is q 1 if the light strikes the core-cladding...
  44. T

    Understanding Light Reflection and Black Bodies in Nature

    One thing that has allways disturbed my mind is the correct understanding of lightinteractions in nature. When we're talking about light reflection (light that is reflected in an arbitrary direction, not like mirrors) is it really reflections or is it new light created by the incoming light...
  45. Chi Meson

    How Does Quantum Probability Affect Light Reflection on Water Surfaces?

    When light is incident on a surface of water, for example, some of the light is reflected and some is transmitted and refracted. As I recall, the percentage of light that gets reflected will be determined by the quantum probability that light will reflect at that interface. First...
  46. F

    Light Refraction/ Reflection/ Etc

    Hi all. I just have a few questions regarding light refraction and reflection. At sunset, the sun seems to be higher in the sky than it really is- correct? What causes this? Which color of light is refracted least by a glass prism? How do each of the colors separate through a prism to...
  47. lavalamp

    Diffraction, refraction & reflection

    I have a simple question to which, I assume, the answer will be quite complicated. I asked my physics teacher this question and all he would say was, "It is known." So without beating me to death with physics can anyone tell me why waves diffract? For instance, electron diffraction around a...
  48. Andre

    Mirage, refraction or reflection

    So what is it? This is not a homework question. But I anticipate a good discussion.
  49. M

    Can Feynman's QED Explain Partial Reflection and Light Communication Speeds?

    Hope this is the right forum. Rather daunting task to pick the right forum when you don't understand what differentiates each topic... Anyhow, I've been reading Feynman "QED The Strange Theory of Light and Matter" (lectures). Actually, I've read it about 3 times, cover to cover. I get some of...
  50. H

    Archived Solve Reflection Problem: Convex & Plane Mirrors 28cm Apart

    A convex mirror and a plane mirror are placed facing each other and 28cm apart. Midway between them and on the principal axis of the convex mirror a small luminous object is placed. If the distance between the two images observed on looking into the plane mirror is 24 cm, calculate the radius of...
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