Waves are disturbances that propagate through space and time. Classically, they travelled through a medium, disturbing the particles but not changing their mean position. Electromagnetic waves/particle-waves need no medium; they are disturbances in their respective fields.

learn more… | top users | synonyms (1)

0
votes
3answers
81 views

An experiment to show sound waves

My 6 year-old son asked me to explain the sound barrier. I think I'm ready to explain, but I wanted to know if I could add a little homemade experiment to show visually how soundwaves are generated. ...
0
votes
1answer
42 views

Derivation of the wave equation from Hooke's law- Generalization question

Following the derivation on the relevant Wikipedia page, I am having a bit of trouble moving from the following line, with the case of 3 particles in a row: $$ \frac{\partial^{2}}{\partial t^{2}} ...
-3
votes
2answers
94 views

Do mechanical waves also carry momentum as well as energy? [closed]

I have read that electromagnetic waves carry momentum because they carry energy, while energy is equivalent to mass. So they carry momentum. But this explanation is in the context of special ...
0
votes
1answer
18 views

When should I use the phase constant in the equations of waves?

In the equations of Waves, I find that somewhere they have used the phase constant and somewhere haven't. While deriving the formula of standing wave they assumed two equation as $ y_1\; =\; y_0\, ...
0
votes
4answers
58 views

Is the speed of sound in air constant?

In Optics lecture we took a formula for the speed of a wave which is: $$ v=\frac{\omega}{k} $$ where $\omega$ is number of complete vibrations per second: $$ \omega=\frac{2\pi}{\tau} $$ and: $$ ...
1
vote
1answer
27 views

Conservation of energy in a sound wave

I have two ultrasonic transducers, an emitter and a receiver, and I'd like to know how the energy of the spherical wave is conserved. I guess the energy is proportional to its amplitude and it ...
0
votes
0answers
32 views

Problem in understanding the interpretation of $-T_0\frac{\partial\psi(z,t)}{\partial t}\,.$

I've been reading in Frank S Crawford's Waves, travelling waves and reflection. Here in the following quotes, the author interprets the term $\frac{\partial \psi(z,t)}{\partial z}$: The power ...
0
votes
2answers
50 views

Is the wave equation a periodic wave equation?

I have seen that in the derivation of wave equation, they always use the periodic property of waves in the derivation. But what about non-periodic waves? Do they have some different wave equation? Is ...
1
vote
1answer
75 views

Why are two speakers at the same volume and distance not twice as loud?

If I have two identical speakers facing me which are adjacent to eachother, playing the same music at the same volume, would it be any louder than having just one speaker at the same volume? If not, ...
1
vote
2answers
44 views

Is a spring shaped like a sine wave?

It's just a casual observation, so I wanted to check it: A regular spring, when not completely compressed, looks an awful lot like a sine wave. The idea of a circular shape stretched out in the third ...
3
votes
2answers
62 views

How does a tranverse wave propagate?

Sound waves can be understood as particles hitting each other and to conserve momentum the vibration travels in air. Each particle transfering it's momentum to the other until it reaches our ears. ...
0
votes
0answers
27 views

Why are photonics fibers called band gap fiber?

Why are photonics fibers called band gap fibers? Do the photonic fibers guide light inside the band gap or outside? What creates the band structure?
0
votes
0answers
15 views

How does an increase in temperature change the width of the central bright for Fraunhofer's single slit experiment?

When coherent light shines onto a metal sheet with a thin slit. There will be an interference pattern with a central bright fringe. If the temperature of the metal is increased, this causes linear ...
1
vote
1answer
42 views

Failure of Superposition principle at high amplitudes

Why does superposition principle fail at high amplitudes. Please answer with respect to transverse waves. If possible, plane progressive transverse waves at best.
0
votes
1answer
53 views

Why does phase of a wave change after reflecting from a denser medium?

Why does phase of a wave change when reflected from a denser medium, but no change takes place in phase during transmission?
0
votes
2answers
29 views

Energy of a wave

Energy density of a wave is given by $$E=\rho\omega^2A^2\cos^2(kx-\omega(t))$$.However for purposes of calculation we use the average of energy.i.e $$E=\frac{\rho\omega^2A^2}{2}$$WHY?
0
votes
1answer
38 views

is there explicit eqution between radiation electromagnetic wave and accelerator a charge that has curve moving path?

i had a basis question i read a rule in electromagnetic when a charge is moving and it has accelerator it will emit electromagnetic wave. now i want to find a explicit equation that describe this rule ...
1
vote
0answers
21 views

What is the highest frequency for ripples on water

I want to transmit sound vibrations as ripples on water, as an experimental audio delay effect. Can I make ripples at audio frequencies, that will travel over about 10cm or more? How about other ...
3
votes
1answer
28 views

Confusion about the shock growth

I am studying Hamilton's & Blackstock's Nonlinear Acoustics. One of the essential phenomena associated with a finite-amplitude (unidimensional, planar) sound propagation is building the shock due ...
0
votes
0answers
11 views

How is the Amplitude and intensity of a sound wave spilt when it splits into three waves with equal energy?

A sound of intensity $27I_o$ is produced at a point. It splits to travel along three different paths. Assume that sound energy is equally distributed among the three parts. Now what is the ...
0
votes
0answers
24 views

How do I find the general equation of a wave propagating through space?

I came to know that general equation of any wave is a function of time and another parameter which depends on type of the wave. According to my textbook, definition of wave is propagation of a ...
7
votes
2answers
634 views

What makes a wave dispersive?

Water waves are dispersive ( longer wavelengths travel faster ) but sound waves in air are not, otherwise we would listen first the high frequencies and the low frequencies after. What decides if a ...
1
vote
3answers
72 views

Derivation of the group velocity

I know that the group velocity of a light pulse is defined as $$\begin{split}v_g&=v_p\left(1+\frac{\lambda}{n}\frac{dn}{d\lambda}\right)\\ ...
3
votes
1answer
74 views

Why do water waves with longer wavelengths travel faster?

When wind blows over the sea, it excites a range of wavelengths. Why do longer wavelengths travel faster?
0
votes
1answer
22 views

Pressure Inverting Reflection of a Sound Wave

How would the frequency and energy of a pressure inverted sound wave compare to the frequency and energy of the original sound? Would it sound any different?
0
votes
1answer
55 views

Interference of light waves question

We were recently asked to solve a question in class which goes as follows: In a modified Young's double slit experiment, a monochromatic uniform and parallel light beam of wavelength $6000$ ...
10
votes
3answers
278 views

Why a ship can't pass through its own wave?

This is a photo of a container vessel. All container vessels are long because they are cruising at high speeds. When a ship is sailing it creates waves. When the wavelength of these waves equal the ...
1
vote
0answers
21 views

What is the relationship between the size of a slit and wavelength in diffraction? [duplicate]

Almost everywhere I see the statement that diffraction gets stronger when the size of the slit is comparable to the wavelength. I would just like to know the logic behind. Could anyone help me please? ...
1
vote
0answers
15 views

Scale analysis for the vertical component of the Boussinesq equation to obtain a complete hydrostatic relation

This is actually an exam question which i have been trying to solve for my studies. Consider the Boussinesq vertical equation: \begin{align} \frac{\partial \widetilde{w}}{\partial t} = - ...
0
votes
0answers
22 views

Intensity of interfering light waves

I had a conceptual question above light wave interference. Suppose that two light beams, each of an irradiance $I$ interfering on an area $A$ of a screen, such that all of the light from each beam ...
-1
votes
1answer
20 views

Progressive and Stationary Waves Amplitudes confusion

In my mechanics lecture, my professor mentioned that standing waves have nodes and antinodes, which is correct. Then he mentioned that in progressive waves, all the points have the same amplitude. ...
2
votes
1answer
70 views

What causes electromagnetic waves to propagate in free space?

In free space, $\rho=0$ and $J=0$, so there are no electromagnetic sources/sinks. Maxwell's equations thus reduce to: $\nabla\cdot E = 0$ $\nabla\cdot B = 0$ $\nabla\times E = -\frac{\partial ...
0
votes
1answer
54 views

Can there be a wave function that is physically possible but is non differerentiable (maybe even non-continous)?

The definition of a wave function demands continuity and differentiability so that it can satisfy the Schrödinger Equation. My question is whether this assumption is necessary for reality. Does ...
1
vote
1answer
28 views

Diffraction grating (finding number of emission lines)

I came across a question on isaacphysics.org where youre given information about a diffraction grating, the spacing of the gaps and the colour and location (in degrees) of 8 different maxima, of four ...
0
votes
1answer
43 views

2D standing wave

When we have 1D standing waves, we can write them as the sum of two propagating wave in opposite directions that give the formula $\sin(kx)\cos(wt)$. When I try to do this for 2D waves (I mean 2D by ...
0
votes
2answers
40 views

Wave reflection

I have a simple question on wave reflection. I know that if I have a progressive monochromatic EM wave and a mirror, the reflected wave will be opposite in phase on the mirror to assure a total E ...
1
vote
1answer
38 views

Newtons corpuscular theory

I am learning about the history and evolution of certain physics theories, one being Newtons corpuscular theory. I am reading that Newton predicted the corpuscles, which make up light would travel ...
0
votes
1answer
35 views

Why must we use mode locked lasers?

Quick question: If I have a laser cavity with a bunch of harmonics under the gain curve: Why do I not always get a pulsed laser? EG: I mean since these harmonics exist in the cavity arn't they ...
0
votes
1answer
47 views

Does the frequency of a organ pipe changes with its diameter? Explain

I am confused a bit does the frequency of a organ pipe have relation with its diameter or not.
0
votes
2answers
83 views

Wavelength and Frequency (Wave travel)

It is true when a wave is traveling in a constant velocity, there is an inverse relationship between a wavelength and frequency. For example, if a wavelength is increasing, frequency should decrease ...
6
votes
1answer
659 views

Liquid wave faster than sound in the above gas: possibility implications

I recently heard that tsunamis (meaning "harbour wave") can travel over 800 kilometres per hour (500 mph), not so far from the speed of sound in the air. May it happen, in general, that a wave in a ...
0
votes
1answer
15 views

Working out the speed of a object by its frequency and a superposition wave?

Say you have 2 loudspeakers facing each other and they are separated by 20m, but are connected to the same oscillator and so both have a signal frequency of 800Hz. I calculated the separation of the ...
2
votes
0answers
69 views

What happens to Newton's Third Law during the reflection of a pulse from a free end?

Well, it is known that a pulse gets inverted when it gets reflected from a fixed support while the polarity of the pulse remains same when the incident pulse gets reflected from a free end. However, ...
4
votes
1answer
51 views

Resultant intensity of two waves

For long I've been thinking about this issue, but ended up with nothing : Suppose you have a point source $S_1$ sending a spherical wave in space of equation $\phi=\dfrac{A_0}{r}\sin(kr-\omega t)$ ...
0
votes
0answers
26 views

What would happen if we try to emanate sound waves from a conic surface? [duplicate]

Say we want to emanate sound waves through a conical surface, what would happen at the tip? How would the waves be?
2
votes
2answers
67 views

How can 2 EM waves null each other at a point but continue to propagate?

how can 2 EM waves (travelling in opposite directions) null each other at a point in space but continue to propagate beyond the point in space where they interact to null each other?
1
vote
2answers
45 views

Double slit with opposite circular polarizers

Let's say I'll send linearly polarized light onto double slit but in front of one slit I'll have quarter wave plate and before the other I'll have 3/4th wave plate (half+quarter? minus quarter?) ...
0
votes
0answers
51 views

Why call it a particle and not a wave pulse?

My physics textbook says that photoelectric emission provides conclusive evidence for the particle theory of light. Apparently, since photoelectric emission only works at certain frequencies, we can ...
0
votes
0answers
47 views

What will be the shape of this graph at $t= \frac {T}{4}$

Consider the following variation with distance x and displacement y of the string at $t=0$ Then what will the shape of the graph be at $ t= \frac {T}{4}$? My Attempt: I feel that the peaks of ...
0
votes
2answers
38 views

Relation between wave functions $f(x-vt), f(t-x/v), f(kx-\omega t)$

I was struck by an answer to this question that made me think about various ways to write a solution to a wave equation. One can write $f(x-vt)$ or $f(t-x/v)$ (as noted in an answer to the above) or ...