Waves Definition and 1000 Threads

  1. Dom Tesilbirth

    The resultant intensity of two interfering waves

    My Try: The resultant field is given by $$\begin{aligned}\overrightarrow{E}=\overrightarrow{E}_{1}+\overrightarrow{E}_{2}=\widehat{i} E_{0}\cos \omega t+\widehat{j}E_{0}\cos \left( \omega t+\phi \right) \\ \Rightarrow E^{2}=E_{0}^{2}\cos ^{2}\omega t+E_{0}^{2}\cos ^{2}\left( \omega t+\phi...
  2. A

    Sound waves inside an inert gas fusion reactor

    Hey, its that under educated guy again, I hope the mighty big brains can spare me my feelings. Anyways, I saw this toy that levitated a ball of water using nothing but sound waves. So naturally I tried to apply this to a plasma and fusion. Using a inert gas reactor, or a fusor for that matter or...
  3. S

    Classical Waves books -- Looking for better textbooks to augment my class materials

    Are there any good textbooks about waves? Like Pain or French except written competently, devoid of mistakes and logical even axiomatic. Ambitious with strong math. Can be old. We were recommended to read Pain but that book is a joke and French is just a simplified version thereof. Problems are...
  4. P

    B Cryogenic storage dewars and EM waves

    I was researching cryogenic storage dewars and read that, "All dewars have walls constructed from two or more layers, with a high vacuum maintained between the layers. This provides very good thermal insulation between the interior and exterior of the dewar, which reduces the rate at which the...
  5. MichaelTam

    Help Needed: Solving y = A sin({2*10^6 ({\pi / 3 -\pi t }) + \phi })

    I know so ## y = A sin({2*10^6 ({\pi / 3 -\pi t }) + \phi }) ## There still some unknown I cannot find, can anyone give me some hint please?
  6. person123

    I Water Waves Over Obstacles: Higher Frequencies Grow, Not Decay

    In general, it seems that higher frequencies of a wave dissipate more than lower frequencies. For sound waves, it explains why you can hear lower pitches from farther away. For a vibrating string or plate, the higher frequencies also dissipate first, with the fundamental fading last. For water...
  7. Poetria

    What is the Error in Linking the Derivatives of the Traveling Wave Equation?

    My reasoning was: $$f_x=cos(x-v*t)$$ $$f_t=-v*cos(x-v*t)$$ so the relation between the two is: ##f_t=-v*f_x## Why is this wrong?
  8. P

    B Question re photons/EM waves and the double slit experiment

    Not a physicist. Background is in electronics over many years. Have recently been "binge" watching youtube lectures on the "dreaded" QUANTUM MECHANICS by various people(Susskind, Feynman et al) and trying to comprehend the whole thing. While I can generally follow the lectures I must admit the...
  9. A

    I Momentum in electromagnetic waves

    Hi all! These days I am brushing up my knowledge on EM Waves. I begin with the introductory level but I don't mind to engage in an advanced treatment of the topic. At the very basic level I had a high school book, the mentions straightway that if the wave carries with it an energy U, it posses...
  10. S

    Finding path difference of EM waves received by radio telecopes

    My attempt: I think ##x## is the path difference so by using trigonometry, I got ##x=d \sin \theta## But my teacher said the answer is ##d \cos \theta## What is my mistake? Thanks Edit: Sorry, I found my mistake. My ##x## is not the path difference
  11. M

    Standing waves between two speakers in phase

    The solution provided in the manual poses that the point halfway between the nodes at each speaker is an antinode of pressure (node of displacement) but isn't that a contradiction to the fact that the speakers are in phase? My first thought was that they must interfere constructively and have...
  12. Barblorrane

    I Speed of EM & Mech Waves: Maxwell's Law Explained

    Based on Maxwell's Law, the speed of light can be defined by: $$c= \frac{1}{\sqrt{\epsilon_{0}\mu_{0}}}$$ Based on that, can we find a medium where a mechanical wave travels faster than a electromagnetic one? If so, how does that works?
  13. MD LAT 1492

    P & S Waves to Strains-liquid solid interface

    Welcoming any relevant literature!
  14. LarryS

    EM Waves Generated by an LC Circuit?

    I am not an electrical or electronic engineer. I am trying to understand how a simple, series LC circuit running at it's resonant frequency can generate EM waves. I believe, based on what I have read, that the frequency of the generated EM waves will be the resonant frequency of the circuit...
  15. E

    A Cosmological gravitational waves

    The exercise is to derive the form of the symmetric, trace-free and transverse gravitational wave perturbation ##\hat{E}_{ij}## to the FRW metric$$ds^2 = a^2(\tau) \left[ -d\tau^2 + (\delta_{ij} + 2\hat{E}_{ij})dx^i dx^j \right]$$First step is to figure out the connection coefficients, which are...
  16. P

    Can someone give me a better intuition of bandwidth?

    Can someone give me a better intuition of bandwidth. The way I see it, is that the bandwidth is the range of frequencies which a signal/wave is allowed to have. This doesn't feel complete though. For example, how can I explain that TDMA, FDMA and CDMA are similar in this sense. As far as I know...
  17. P

    I How does a standing wave form?

    I understand how waves undergo superposition. However, for a standing wave, the reflected wave is a mirror opposite of the incoming wave. By the superposition principle, won’t the 2 waves add up to 0, at all points?
  18. gepdiana

    How Do Electromagnetic Waves Propagate in Space?

    Hi everyone, I m not a physicist and I don't really speak english... please forgive me if I write any "rubbish". I'm quite curious, and I was wondering how do electromagnetic waves travels. I mean, from a "point" source, they propagate in every direction (I've been told) so I tend to imagine...
  19. D

    I Gravity Wave Propagation: Negative Energy Pulse?

    At 0:51 in this simulation video there seems to be a brief moment upon merging that these singularities produce what appears to be negative gravitational "Spike?" that seems to bulge spacetime in an opposite metric compared to normal spacetime flatness. Is this a quirk of the simulation or is...
  20. Z

    I Longitudinal waves on a string

    Good day to everyone, I kindly ask for your help. My question is: "Does a string have to be under tension, to transmit longitudinal waves? Why is it so?" I have trouble finding relevant scientific articles regarding the question and for reasearching "longitudinal waves on a string". If anyone...
  21. J

    Standing waves (graphing) homework question

    Points A b AND C are shown in first diagram Im confused about question three... I feel like its related to wave length but the fractions are throwing me off.
  22. J

    Waves -- How does increasing tension affect frequency and period?

    Using this stimulation: https://phet.colorado.edu/sims/html/wave-on-a-string/latest/wave-on-a-string_en.html It looks like frequency is decreasing as I increase tension but online it says frequency increases as tension does. Also, I am unsure about what happens to the Period
  23. J

    Waves - General question about Damping and how it affects a propagating wave

    I think increasing the damping would decrease the amplitude and increase the Period (T). But, what I'm really unsure about is the frequency, wavelength and wave speed. Would it be no effect on those three? Because if dampening acts like friction, wouldn't it slow down the wave/ increase speed?
  24. D

    B Gravitational Waves: Comparing Effects on Earth

    If we compare 2 scenarios... A) 2 solar mass black hole hyperbolic flyby of Earth at 5000km/s far enough not to cause a tidal disruption event vs B) an extremely close binary pair of 1 solar mass black holes whose barycenter hyperbolically travels past Earth at 5000km/s, also far enough not to...
  25. D

    Why smooth spherical waves with attenuation are only possible in 3-D

    Hi all, My question is about the attenuation and delay terms in part (1). what are attenuation and delay terms describing in physical phenomenon? thank you. What do "attenuation" and "delay" mean in terms of real-life physical phenomena? Consider the wave equation for spherical waves in...
  26. A

    I Can the energy in two waves cancel out? If so, why?

    I know the answer would be yes, but why? In class, I learned that energy is scalar and cannot be negative (at least in undergraduate class). Thus adding two sources of energy should result in a higher level of energy in general. But here for wave, if we have 2 waves that do destructive...
  27. A

    Using constructive interference of audio frequency waves to lower distortion

    Hello everybody . I would like to ask you for an opinion. audio waves passing through a horn or waveguide experience a small or relatively large distortion. do you think it is possible to eliminate distortion by making use of constructive interference?
  28. T

    Harvesting the energy of sea waves using capacitance

    Hello. I have a question related to capacitance. here is another mechanical solution to harness wave energy. Can changing capacity of the capacitor be used to harness wave energy? Let's say we envelope conductive plates in plastic and submerge them in the ocean and the water in between them...
  29. G

    I Alcubierre Drive & Gravitational Waves: Alien Effects?

    Suppose some aliens travel to our solar system after seeing our radio broadcasts using an Alcubierre drive. Would it not create a notable gravitational disturbance? Or does it leave spacetime undisturbed around it?
  30. M

    Oblique shock waves: how to find the wedge angle for trailing shock?

    Hi, I have a question regarding oblique shockwaves. Question: How can we determine what the wedge angle is for the shockwave in a situation? Context: This problem here shows an oblique shock wave on the trailing edge of the body and it simply states that the wedge angle is 6 degrees. Why is...
  31. J

    Find maxima angle of two interfering waves

    I drew a diagram in the attached files as well, but the the scenario seems to be the same as the double slit experiment, but I don't understand why the answer contains cos instead of sin.
  32. veraamorim

    What is the relationship between refraction and giant waves in Nazaré?

    The waves of Nazaré start because of a storm in the open sea. The winds cause a disturbance on the surface, transformed into energy. When the depth is great, the propagation of the waves (energy) is practically constant. As they approach the coast, therefore in shallower places, the wave length...
  33. veraamorim

    B Next Generation Planetary Missions Hunt for Gravitational Waves

    Spacecraft heading to Uranus and Neptune in the next decade could be used to investigate gravitational waves as they venture into the outer Solar System. That is according to a new study by a team of Swiss and Danish researchers, who say that examination of the radio signals from far-flung...
  34. H

    Where are the waves out of phase with each other by π radians?

    I know that at the antinodes, the diffrence is pi radians and i got 0.25, 0.75, 1.25, and 1.75. for the position of antinodes. but the answer is x = 0.75 m, 1.25 m. I can use drawing to obtain the answer, but my calculation gives me 0.25, 0.75, 1.25, and 1.75. Where am I doing wrong? Thanks!
  35. H

    How Does Angular Frequency Relate to Cycle Frequency in Wave Equations?

    Explanation: y1=6cos(180t) +) y2=6cos(186t) y1+y2 =6cos(180t)+6cos(186t)y =6(cos(180t)+cos(186t)) cos(A)+cos(B)=−2cos((A+B)/2)cos((A−B)/2) y=6(−2cos((180+186)t/2)cos((180−186)t/2)) y=−12cos(183t)cos(3t) y=(−12cos(3t))cos(183t) Comparing with the standard equation...
  36. duchuy

    Calculating Phase Difference and Interference with Laser Light

    Hi, I need help finding the phase difference between the two rays converging at F'. I was given this figure, the distance between the lenses is 10cm, the thickness of the lense is 1micrometer and the indexes are on the figure. The light is a laser in which lamda = 500nm. I tried to write down...
  37. C

    I Quantum stuff is neither particles nor waves

    When I asked my professors about quantum interpretations like whether it is particles or waves in the double slit experiment. They always say it is just quantum stuff which is neither particles nor waves, so one must not describe them at such. So why do we have so many interpretations. Why not...
  38. lomidrevo

    I Gravitational Waves Emitted by a Binary System

    Let's assume a binary system with an inclination angle ##i## (angle between the orbital plane and line of sight). Then, according to this source - equations (128) and (129) - for the amplitudes of the tensor polarization modes ("plus": ##+## and "cross": ##\times## polarization) I could write...
  39. X

    Polarization of EM waves is preserved after reflection/refraction -- Why?

    Hello, here's my question: during the usual derivation of Fresnel's equations, it is assumed that an incident EM wave (plane monochromatic) is transverse electric or magnatic and that it keeps this nature after reflection and transmission. How can this be proven? Thank you!
  40. person123

    I Computing the Speed of Traveling Waves in 2 Dimensions

    I have a 2-dimensionsal smooth function ##f(x,y,t)##. There may be multiple traveling waves across the domain. None of them are precisely traveling waves (the shape of the wave changes as it travels). Here is how one of these waves would look in 1-dimension: I want to find the speed of these...
  41. R

    Can heavy objects be used to modulate light waves with small amplitude?

    Question: Can heavy objects be used to operate light waves with smaller amplitude, or waves with high amplitude be used to operate objects with small mass? This is a diagram I drew that illustrates my point. Heavy objects are meant to be celestial bodies, and the light source generates a beam...
  42. L

    I What happens when two waves in counter phase affect a conductive material?

    i am writing this message after a short consultation with kuruman. if there are two waves emitted by the same source then with the same direction, but these waves are in counterphase link...
  43. 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...
  44. B

    Electromagnetism -- What do charges have to do to create EM waves?

    I am not sure, but I think the answer is between acceleration and velocity.
  45. LCSphysicist

    I Boundary conditions for TM and TE waves

    Theta in the incident angle Phi is the refraction angle '' denotes everything that propagates to the other medium, that is, everything related to refraction ' denotes the reflection in the original medium I am rather confused, would appreciate any help. I see the second equation of TE is...
  46. H

    I Are electro-magnetic waves the same as the wave function?

    When studying classical mechanics we are told that light is the propogation of electromagnetic waves. This makes perfect sense, as I can imagine these fields behaving this way, and in turn have an associated wave length. When learning about QM, I have heard that the wavelength of a (any)...
  47. G

    I Electrostatic waves in a plasma

    I’m having A bit of confusion regarding this. In a plasma by turning on an electric field ,wouldn’t this cause an oscillation of the electrons about the ions,effectively a oscillating dipole thus inducing a magnetic field, by amperes law? My text (plasma physics by F.Chen )has curlE =0 I’m not...
  48. C

    Max velocity of a vibrating loud speaker membrane given sound intensity

    My attempt: p and T allows us to calculate ##Z=402 \frac{kg}{sm^2}## using ## Z=p*\sqrt(\frac{\gamma*M}{R*T})## . The sound intensity level at 10 meters allows us to calculate the intensity at 10 meters to be I=10``````^{-7} W/m^2 using ##50 = 10*log(I/I_0)##. Then, using the formula...
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