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)

8
votes
3answers
707 views

Why should a solution to the wave equation be finite?

Given the wave differential equation $$\frac{\partial^2 y}{\partial t^2} = k\frac{\partial^2 y}{\partial x^2}$$ Any function that satisfies the wave differential equation represents a wave ...
0
votes
2answers
2k views

What is a wave? What is a particle?

I am reading a David Bohm book on quantum theory. He says the idea that light is both a particle and a wave is incompatible: (1) we know light has particle-like properties through the photoelectric ...
3
votes
2answers
100 views

How would a sound mirror work?

Context: We all know that by galvanizing a plate with a silver coating, this plate will have a very high reflection coefficient and act as a mirror for EM radiation (not for all $\lambda$ ranges of ...
3
votes
4answers
211 views

What is an electromagnetic pulse?

Is an electromagnetic pulse a plain electromagnetic wave with one peak?
0
votes
1answer
32 views

Can a phase array evoke a standing wave at a focal point that has a much higher frequency that the constituent emitted frequencies?

This is a phased array: How can you focus sound? It can focus many waves of weak radio wave or light into a single focal point that's very strong. Now imagine that we delay half of the emitters by ...
0
votes
2answers
151 views

Is it possible to have both a conduction current and a displacement current at the same time?

According to Ampere's law, is it possible to have both a conduction current and a displacement current at the same time? In the classical derivation of the displacement current using a parallel plate ...
3
votes
1answer
71 views

Superposition of electromagnetic waves and energy localization

Sorry for the long question. I didn't know how to make it shorter. I'm trying to understand how energy is spatially localized in an electromagnetic wave. My premises are: Electromagnetic energy is ...
2
votes
1answer
103 views

Coherence length requirement for interference

One property of light sources that is usually stated, which is of particular importance when trying to create interference fringes, is the coherence length (or coherence time). The equation for the ...
14
votes
2answers
798 views

Why are electromagnetic waves not able to pass through a hole with a diameter smaller than the wavelength? [duplicate]

I am doing research on Faraday cages for school, and I want to know how it works. Faraday cages can have holes in them, and if the diameter is smaller than the wavelength of waves you want to block, ...
0
votes
1answer
88 views

Why are there dead zones near an antenna using the sky-wave propagation system?

I have heard in my class that there are dead zones near the antennas which use the sky-wave propagation system. I have also been told that cell phones are unable to receive signal near the antennas. ...
1
vote
2answers
84 views

Will the frequency of the reflected wave of a moving source be shifted by Doppler effect?

I want to know if there is a moving source that emits wave to a reflecting object like a wall for example, then, will the frequency of the reflected wave be shifted because of the Doppler effect. As ...
0
votes
1answer
111 views

Problem with sound intensity equation in displacement amplitude form

The sound or wave intensity is defined by energy transfer rate with time (power) per unit of area: $$ I = \frac{P}{A} \tag{1} $$ so this equation makes sense since the denominator is the area of the ...
2
votes
3answers
81 views

Is wave superposition always equivalent to wave interference?

I'm confused when using these 2 words "wave superposition" and "wave interference" since their definition is very similar. So, are these 2 term the same?
1
vote
1answer
53 views

How does diffraction cause maxima and minima on a viewing screen

I have a problem in understanding the diffraction phenomenon. At first, it is described in simple way If a wave encounters a barrier that has an opening of dimensions similar to the wavelength, ...
32
votes
7answers
4k views

Why is it so easy to create audible sound?

Context Why is it so easy to create audible sounds in life with basically anything? Putting your cup of coffee on a table comes with a sound Turning a page of your book comes with a sound Even ...
1
vote
3answers
131 views

Relation between wavelength and system size

We always say that when a given light wave interacts with atoms bound in a molecule, only waves with wavelength close to the inter-atomic-spacing are able to probe the system. In other context ...
4
votes
2answers
133 views

Light wave crossing media and the relationship between speed, wavelength, and frequency

There are many threads on this topic (like this one) but one aspect about the equation $ v = \lambda\nu $ still confuses me. I have read that frequency does not change when light crosses into ...
0
votes
1answer
51 views

Is there no way to create an arbitrary wave on a string fixed at two ends?

My question concern standing waves on a string with 2 fixed end. As there is one wave created, it will be reflected when it reaches one end and create another identical wave with opposite direction ...
0
votes
2answers
143 views

Does wave interference happen only to same frequency waves?

As the title says, from books and results from internet, I find that examples of wave interference always have the same frequency, only different in phase constant. So, I'd like to know if wave ...
0
votes
1answer
25 views

The wave function of transverse one is different from longitude one for convenience?

I use the book Fundamental of Physics Hallidays&Resnick 10th Edition Jearl Walker to study in my physics class while I got myself University Physics with Modern Physics Sears, Zemansky 13th ...
0
votes
2answers
87 views

Solution of one dimensional wave equation by variable separation method

When solving the One dimensional wave equation by variable separable method, we equate left-hand side and right-hand side to a constant which is negative in nature. Why has the constant be only ...
0
votes
1answer
40 views

What unit of distance to use when calculating power loss?

80% of Earth's atmosphere is within 10 miles of Earth's surface. I know that power attenuates inversely as the square of the distance within the atmosphere so it occurs to me that a 50,000 watt signal ...
7
votes
3answers
890 views

Can polarized light be unpolarized again?

I was just wondering if there could be a process that could unpolarize polarazied light. Is that possible?
1
vote
1answer
69 views

Does rain jam radio signal?

I have experienced several times that heavy rain seems to jam the signal a radio of a bus receives. The only explanation I have is that the rain drops also become weak emitters, if a radio wave hits ...
2
votes
0answers
61 views

Diffraction grating from first principles

I have realised that a lot of books and online resources fail to give a detailed treatment of the derivation of the diffraction grating interference pattern. Normally only the result is stated. I was ...
0
votes
2answers
82 views

Coupled oscillators and Normal Modes

Consider we have a system consisting of 2 arbitrary masses and 3 arbitrary springs connecting them horizontally and between fixed walls, and we want to obtain the motion of each mass after we input ...
1
vote
1answer
70 views

Why does the bass range of phase mismatched speakers show more interference than the treble range?

If stereo speakers are connected to the amplifier "out of phase," one speaker is moving outwards when the other is moving inwards.This results in a weakness in bass notes, which can be corrected by ...
5
votes
3answers
167 views

How do we know that the Fourier transform of space is momentum?

How do we know that the Fourier transform of real space $x$ is the momentum $p$ space or for energy and time, receptively? What's the mathematical process and physical logic?
0
votes
0answers
92 views

What affects the period and the frequency of a longitudinal vibration?

In a lab experiment, our objective is to observe the characteristics of longitudinal waves/vibrations. If we changed the mass and amplitude, I feel that they either affect the period and frequency of ...
0
votes
2answers
198 views

What's the physical interpretation of an arbitrary normal mode for masses and springs?

Consider the following system consisting of 3 masses and 4 springs : I have learned that this system posseses three normal modes, corresponding to its three natural frequencies, say ...
0
votes
1answer
22 views

Why doesn't linear wave theory produce phase velocities that agree with each other?

I'm not sure I understand the dispersion relationship for water waves. According to Wikipedia, the wavelength of ocean wave at arbitrary depth is given by: \begin{equation} ...
0
votes
3answers
74 views

Does there exist a hyperbolic relationship between frequency $\omega$ and wavenumber $k$?

As the title states, is it possible to derive a hyperbolic relationship in the form of $\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1$ between frequency $\omega$ and wavenumber $k$ I have tried to start this ...
2
votes
4answers
150 views

Space orientation of light waves

Recently I've started to be really intrigued with the electromagnetic spectrum and bumped into this problem: According to the wave theory of light (or any electromagnetic wave, really), the magnetic ...
1
vote
0answers
51 views

Wave-Particle Duality in the Confinement of an Electron in a Box [closed]

According to the wave particle duality, one can say that an electron is both a wave and a particle. If we confine it in a box, it can only form standing waves at particular wavelengths, which leads ...
0
votes
0answers
15 views

Comparing the Intensity of a Point on the Screen to the Central Max (Double Slit Experiment)

For (b), I know that the following equation will give me the ratio of the intensities: $cos^2(\frac{dsin(\theta)\pi}{\lambda})$ I do understand the theoretical basis behind the formula. However, ...
0
votes
1answer
45 views

Speed of an electromagnetic soliton in free space

What is the speed of an electromagnetic soliton in free space? Is it equal to 'c' ? P.S. My understanding of the Fourier transform says it's not.
0
votes
2answers
40 views

How do we count beats?

Books say that one beat constitutes two successive maxima of sound intensity with a minima in between. This is confusing me as the definition of beat period says - it is the time interval between two ...
0
votes
3answers
191 views

Question on open organ pipe

Although open organ pipe is open on both ends, how standing waves are produced in a open organ pipe. Can someone explain with more clarity ?
2
votes
2answers
161 views

Are solutions coordinate invariant?

In the case of electromagnetism, we can solve the sorceless wave equation in Cartesian coordinates ($x$,$y$,$z$) getting plane waves as solutions: $$ u(x) = A(x-ct) + B(x+ct) $$ and actually I am not ...
0
votes
2answers
104 views

Plane polarized light?

I have heard about plane polarized light: light wave which has vibration in one plane. My curiosity forces me to ask a doubt, is there any way to produce polarized light wave which has vibrations in ...
3
votes
1answer
121 views

Waves and Newton's Third Law

I'm a really newbie in Physics trying to understand a bit about waves. Firstly, i'm using the Wikipedia's definition of wave , that is, as energy traveling through a medium/space without ...
5
votes
2answers
303 views

How does an acoustic guitar amplify its sound?

An essential part of a guitar is its hollow body. Without it, the strings wouldn't be very loud; as far as I know, the purpose of the body is to set up some sort of resonance and make the sound ...
1
vote
0answers
27 views

Unusual waves and one of its parameter

I'm messing up with this java app on the web about waves on a string and i'm really curious about something. The java app is the following : ...
0
votes
1answer
69 views

Why is $B=\frac{1}{\omega} k\times E$?

Why can we derrive from $B=\frac{k}{\omega}|E|$ the formula $B=\frac{1}{\omega} k\times E$ ? Obviously, because they are perpendicular, but why is it mathematically legitimate?
0
votes
2answers
63 views

Why is sometimes the wave function written as $\exp(i(\omega t-kz))$, so ωt and kz are switched?

Is it legitimate to write $-\exp(i(kz-\omega t))$ as $\exp(i(\omega t-kz))$?
3
votes
1answer
80 views

Quantum Wavefunctions Without Space

A handful of physicists have a rather peculiar definition of 'nothing' in terms of cosmology. Their claim is that the Universe, assuming it has 0 total energy, could have arisen from nothing but ...
0
votes
1answer
58 views

Intensity for Single-Slit Interference Pattern

In the derivation for the equation for the relative intensity of a single-slit interference pattern in my textbook, there is an assumption that I find a bit fishy. I know this equation works, so it ...
0
votes
1answer
40 views

Standing Waves. Two questions. Please help! [duplicate]

Every time I read an article/text about standing waves they seem to specifically mention that whenever a wave pulse hits a hard boundary it gets reflected back with it's phase changed through 180 ...
5
votes
3answers
265 views

The ubiquitous Planewave Ansatz

In physics, the planewave ansatz (meaning: an educated solution guess) is very ubiquitously used, when solving differential equations, in different domains of physics. E.g. to solve the dispersion ...
1
vote
1answer
44 views

Does Red shift affect electron waves? [duplicate]

According to the De-Broglie Wave Hypothesis an electron can be considered to be a wave. Red Shift occurs due to the expansion of space(Cosmological red shift), which must expand even on the scale of ...