# Tag Info

### A question of energy creation/transfer

Almost certainly not. From conservation of energy, we know that the total energy released by dropping the block is equal to the potential energy given up by the block. But the water waves are not the ...
• 28.8k

### A question of energy creation/transfer

The law of conservation of energy tells us that the energy in the waves can be at most equal to the difference in potential energy between the rock in its initial position and the rock in its final ...
• 57.6k

### Need clarity about EM wave generation

You don't need to "accelerate" current through a wire to make EM waves, even if a current is flowing through a wire at constant rate the charges are still being accelerated by the magnitude: ...
• 402

### Reflection and Transmission Coefficients in Electromagnetic Waves in a Metal with Dispersion

For low frequencies (in Gaussian units), ${\bf B}=\sqrt{\frac{4\pi\sigma}{\omega}}e^{i\pi/4}{\bf{\hat k}\times E}$. Put this into the usual derivation of R, which should be close to 1. There's no ...
• 1,817
Accepted

### What happens "Actually" after waves collide?

Ordinary waves (like those in water or air) pass through each other (they temporarily add up together) and then emerge unchanged, as long as their amplitude is not extreme. Downstream from their ...
• 96.7k

### Need clarity about EM wave generation

The charges produce an electric field all the time, even when they are not moving. This means that electric charges sloshing back and forth along a wire will produce a mixture of time-varying E and M ...
• 96.7k
1 vote

### Need clarity about EM wave generation

First, consider a simple dipole antenna. In its immediate vicinity it produces an electric field from end to end, and magnetic fields in circles around its axis. These fields are pretty close to ...
• 28.8k

### What happens "Actually" after waves collide?

When waves collide, they interact with each other through a process known as interference. There are two main types of interference: Constructive Interference: This occurs when the peaks (high points)...

### Creating pure monochromes by separating constituent waves

A filter that removes all frequency components outside a finite bandwidth, (compact support), must have an infinite long impulse response, see the Paley-Wiener theorem. As a consequence, no signal ...
• 20.2k

### Creating pure monochromes by separating constituent waves

No filter will produce an ABSOLUTE 'pure monochrome'; there are line width limitations in colored-glass items, diffraction gratings have some non ideal features that are related to the 'blaze' ...
• 10.1k
1 vote

### Wave with mass transport?

There is more to the story about whether matter has net motion / displaced i.e. transported (spontaneously advected), in the linked video there is what is called stokes drift, and also the next link ...
• 41

### Why do airplanes sound louder when its cloudier?

See sound refraction says that the atmosphere during cloudy weather is lower towards the ground and hotter towards up, so more sound then usual get reflected back towards the ground not dispersing ...

### Why do airplanes sound louder when its cloudier?

I will assume the airplane is below the clouds in your question. Apparently the main effect of clouds on the sound of an airplane is due to reflections of sound waves. They reflect on the clouds above ...
Accepted

### Can taut membranes and strings that are clamped at both ends propagate non-standing waves?

Mathematically, a wave is a solution of a wave equation with the appropriate boundary conditions. A wave equation alone does not define a wave. Now, if we have hard boundary conditions - like clamped ...
• 62k
Accepted

### How to "rectify" this wave-equation derivation for Longitudinal waves?

Yes, OP is right. In the discretization (1), OP's professor is effectively finding the Hooke's force at the position $x-\frac{1}{2}\Delta x$ and $x+\frac{3}{2}\Delta x$, which are the external forces ...
• 209k
1 vote

When $u_{tt}$ is identically zero we have a static situation. A static electric and/or magnetic field for example. Or a body under static stress. There are no waves. Edit: Besides static situations, ...
• 16.9k
1 vote

### When a taut string is plucked, what will be the direction of the transverse wave's propagation?

Wherever you pluck the string, you will create two instantaneous wave packets - combinations of waves of many different wavelengths - one travelling in each direction along the string. However, once ...
• 57.6k
Accepted

### When a taut string is plucked, what will be the direction of the transverse wave's propagation?

if you pluck the string precisely at the midpoint of the string's length? There will be 2 waves, propagating in opposite directions with transverse amplitude = plucked-amplitude/2
• 94
Accepted

### Linear-array diffraction beam splitter

Figured it out. The GDCalc example uses a Gaussian beam as the incident field. In order to see the correct number of diffracted beams, the waist of the Gaussian beam needs to be increased from the ...
• 284

### How was the speed of colored light measured in a vacuum?

The experiment that I am aware of which places the tightest limits is Schaefer. Severe Limits on Variations of the Speed of Light with Frequency. phys.rev.lett. 82:4964-4966. 1999. https://arxiv.org/...
• 105k

### How was this equation for the stability of a finite difference model Wave Equation derived? Von Neumann analysis?

Again, a partial answer, justifying a bit Pitchoune answer. This is, I think, a basic Von-Neuman analysis. Discretize the equation according to the discretization given in the article (be wary of some ...
• 1,508

### What is the difference between a pulse and a wave?

As the other answers have noted, a way to draw the distinction is to note that a pulse and a wave have in common that they are disturbances or vibrations of a medium that propagate through it, while ...
• 527

### How was this equation for the stability of a finite difference model Wave Equation derived? Von Neumann analysis?

Here is some partial answer that misses some steps/info to be complete and rigorous, but should be enough to explain the derivation. Firstly, since $\sigma_0$ doesn't appear in the formula, I'll ...
• 101

### Waves, energy and matter

I'm not a physicist, and I'm not sure how the physicists will vote on this one; but IMO, instead of saying that a wave transports energy, I think it might be closer to the truth to say that a wave is ...
• 15.7k

### Waves, energy and matter

What is the physical reason why a wave (mechanical or electromagnetic) can transport only energy and not matter? An electromagnetic wave, by definition, describes wave behavior related to photons. ...
I am pretty sure that there is an error with one of the equations. Start from $$2PQ + P\delta + Q\delta \sinh\left(\xi H\right) \sinh(\eta H)=0,$$ where I've already assumed small angles. Now, If you ...