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.

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Does mechanical resonance of an object changes in different surrounding medium?

When comparing mechanical resonance of an object (for example string) in air and in water, does the resonance frequency changes? My guess is that it does change because the surrounding medium will ...
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83 views

Need help visualising transverse waves

From studying waves I find that I can visualise longitudinal waves where the wave propagates in the direction of the displacement. However I don't understand what causes the propagation perpendicular ...
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36 views

Query regarding interference

In Young's Double Slit experiment, why is it that two waves vibrating perpendicular to each other doesn't show interference? I know that for interference to happen, the waves must be coherent ( i.e., ...
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209 views

Infinite potential square well solutions

My question is about understanding the different solutions of the potential square well. Imagine a square well defined this way: $$ V(x) = \begin{cases} ∞&\,{\rm if} x<0 \\ 0&\,{\rm ...
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2answers
80 views

Question about the shape of the waves [closed]

What is the molecular level reason behind the pattern (sine function) of the waves?
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343 views

How/Why does voltage reflect?

I'm trying to understand antenna theory again, and I'm again stumped by the concept of VSW (voltage standing waves). I understand standing waves, I remember these from a physics clases, however I do ...
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144 views

Why does a street light cast a wavey shimmer across the water (at night)

See image You will have to zoom in. Why is the reflection a wavey one? Could someone explain how this is occurring, to the layman, (with the style of feynman if possible -heh) :)
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322 views

What type of electromagnetic radiation strikes the Earth's surface the most?

If you can could you lists the types of light from the greatest amount to the least amount (Ex: Visible, Infrared, Violet).
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164 views

Wave packets Group Velocity

For the the group velocity of a wave packet, the group velocity is the partial derivative of omega with respect to the wavenumber, what does this mean? I thought that for some given wave packet both ...
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2answers
188 views

Uncertainty and wave-trains

My textbook and the following extract from feynman's lectures present the same idea regarding wavetrains and uncertainty in their wavelengths. Why is it that a wavetrain confined to some space has an ...
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948 views

why does the phase change when wave reflects from rigid boundary [duplicate]

when the wave is reflected from open end there is no phase change but when it reflects from the rigid surface its phase changes. in open surface its phase change is 0 and in rigid surface its phase ...
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3k views

Understanding formula for wave displacement

I have a brief question regarding the formula for wave displacement that I've just encountered. My textbook says: For a simple plane wave, we have, for a simple harmonic with displacement $u$: $$u ...
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201 views

How does one find the wave velocity and the phase speed?

While I was studying beats, I tried to find a displacement function of any particle in the most generalized form. I ended up with $$y=2A\sin(\pi(t-x/v)(f_1+f_2))\cos(\pi(t-x/v)(f_1-f_2)).$$ Now, ...
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117 views

Can a stream of photons to be an environment for carrying light?

As the air molecules are environment for carrying sound waves, could stream of photons be environment for carrying electromagnetic waves? What contradictions cause this assumption in the existing ...
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11k views

What is the formula for max kinetic and max potential energy of a spring?

What is the formula for max kinetic and max potential energy of a spring?
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341 views

Width of Gaussian Beam and Refractive Index

I know that in free space, the width of a Gaussian beam can be written as $W=W_0\sqrt{1+(\frac{z}{z_0})^{2}}$. However, I was wondering if it was possible to express this width as a function of ...
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145 views

Percentage increase in the length of pendulum

I'm struggling with a physics question : What should be the percentage increase in the length of the chord of a pendulum for the period increased by 1%? The answer is 2%. I tried with $w = 2 \pi/T ...
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1answer
241 views

Wavefronts and phase velocity faster than $c$

Lets assume we have parallel wavefronts in a glass of water: and we put an inclined rod on the water surface: related to a very small inclining, Vy velocity is greater or much greater then Vx ...
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602 views

Why is Polarization of a wave important, and what happens when a wave is polarized in all three dimensions?

I don't quite understand this, I understand that given a wave traveling in a certain direction, it will be polarized in the direction its not travelling in, so if its travelling in the Z direction, k ...
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381 views

How much energy is contained in a 40 meter wave?

Consider a wave that stands 40 meters high in the sea on very deep water. How much energy would approximately be contained in this wave if it was 100 meters wide and had been produced by wind? Is ...
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955 views

Wave diffraction explanation [closed]

I'm trying to understand wave diffraction and I found this wikipedia article. It's in Czech so I'll explain a bit. I'm interested in the 4 images I couldn't find on english wikipedia. The first one is ...
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21 views

Disparity between two texts on intensity and phase interference - which is right?

So, I'm learning phase interference. Imagine we have two waves. $$ E_1 = A_0sin(wt) $$ and $$ E_2 = A_0sin(wt+\phi) $$ With $$ \phi = \frac{2\pi}{\lambda}dsin(\theta) $$ Which is the path ...
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55 views

The general equation for a wave packet derivation? [closed]

On Wikipedia it gives the general equation for a wave packet (and therefore for a wave?) to be: $$u(x,t)=\frac{1}{\sqrt{2\pi}}\int^{\infty}_{-\infty}A(k)e^{i(kx-\omega t)} dk$$ I have been trying to ...
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51 views

Why is wave a function of volts?

I'm looking at a beginner's book on Fourier and waves, and the very first graph shows a periodic wave where the horizontal axis is time (msec) and the vertical axis is something noted as "MAG(V)" ...
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43 views

Understanding wave packets, in particular matter waves, dispersion and point particles

Here is what I have gathered so far: Particles like an electron (i.e. with rest mass) can be represented as matter waves (deBroglie). The matter wave of a particle can be modelled a wave packet. A ...
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24 views

How can I add two sound waves without reaching distortion - always keep them under a certain value?

I'm working on a program that adds sound waves on top of each other. I read that the best way to do that (correct me if I'm wrong) is to simply add them together. However, this way I easily reach ...
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36 views

How do particles in a wave make the next particles move?

i only know few things about waves,but this question just popped up in my mind. I already know that the particles transfer energy to each other,but i do not know HOW they do it! The truth is that i ...
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27 views

Spherical waves superposition [closed]

If two spherical waves are produced by two sources $S_1$ and $S_2$ as described in the picture From the superposition principle, we know that : $$\Psi(M,t) = \Psi_1(M,t) + \Psi_2(M,t) = ...
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36 views

If the phase velocity is different from the group velocity, why does the high-frequency wave remains fixed with the low-frequency envelope?

Phase velocity is the velocity of the high-frequency wave inside the envelope. While group velocity is the velocity of the low-frequency wave that makes the envelope. If these velocities are ...
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45 views

can a wave on rope placed away from gravity go on forever?

we can make waves on a rope like we produce waves on a whip. assume that my rope(which is pretty long) is in space and i produce a wave on it at a point the rope is connected at the two ends. would ...
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26 views

Is difference in wave number always small?

Over the last few days I have been looking at a derivation of group velocity. The derivation is the one shown in this question Deriving group velocity. I have seen this derivation in many places, and ...
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95 views

Field Vectors and satisfying Maxwell's equations

If I have an electric field that its direction is parallel to the direction of the wave propagation, it will not satisfy Gauss's law for vacuum. However we can say it satisfies Gauss's law for ...
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97 views

Confusion in understanding the concept of beats

. . .it is the combined vibration or disturbance basically having the average of the combining frequencies, but with an amplitude that varies periodically with time-one cycle of this variation ...
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71 views

Relation between sound waves and air molecules

The following was written in my book When sound waves travel in air, air molecules do not move. When wind blows,air molecules move. This produces variation in velocity of sound waves. The first ...
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107 views

What is the physical significance of the negative amplitude of a light wave?

I want to understand what is the physical significance of negative amplitude of a light wave? In an ac electrical circuit, I understand that negative amplitude signifies the amplitude measured when ...
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31 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 ...
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138 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 ...
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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 ...
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1answer
38 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 ...
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78 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 ...
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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 ...
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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 ...
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1answer
50 views

How did the Huygens probe use EM waves to measure wind speeds on Titan?

In the Wikipedia's article on Huygens spacecraft, it was mentioned that one of the experiments was to measure the wind speeds on Titan by Doppler wind experiment. To quote the exact lines, it was ...
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1answer
109 views

What influences the intensity of a wave? Frequency vs Amplitude

So, in school, I have been taught that $I$ is proportional to $A^2$. However, when I look at the equation $E = h\cdot f$, I see the frequency has an impact too on the intensity! Now, if a sound wave ...
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161 views

Would this Produce Thrust? (Photon Momentum, Speed of a Pressure Wave)

This thought occurred to me after I began reading about the EM drive, and I know there are a lot of theories out there on how that works/doesn't work, I'm wondering why this solution wouldn't make ...
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36 views

Tranverse electromagnetic waves

TEM waves do not exist in waveguide. Is this the correct explanation- Both curl and divergence of TEM are zero inside the waveguide and because of the boundary conditions (electric field zero at every ...
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141 views

How does Huygens Principle explain interference?

How exactly does Huygens theory about the propagation of wavefronts account for interference?
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123 views

What is matter made of in the light of Quantum Mechanics? [closed]

I've always wondered what matter (particles, force particles, etc.) was actually made of considering the fact that quantum mechanics has shown us that particles can actually act as a probabilistic ...
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41 views

Direction of the particle's motion

^ y | | |--------------> x Above I have labelled the axes of the graph. In the figure we can see that the direction of the particles motion is downward ...
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59 views

Derviation of group velocity

I am working thru a derivation of the group velocity formula and I get to this stage: $$y=2A\cos(x\frac{\Delta K}{2} -t\frac{\Delta \omega}{2})\sin( \bar k x-\bar \omega t)$$ Then all the derivations ...