# Questions tagged [waves]

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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### Electromagnetics - how to choose a proper normal vector?

In D.K.Cheng's equation 8-29 he makes the following correlation between the magnetic field intensity $\mathbf{H}$ and the electric field intensity $\mathbf{E}$ in an electromagnetic wave. Where $\eta$...
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### Waves velocity on a cosmic string

I'm trying to understand a few things about cosmic strings in cosmology. Consider a single string of energy density $\rho$ and tension $\tau > 0$. I don't assume $\tau = \rho$, as apparently most ...
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### Diffraction pattern for L-shaped slit

Suppose we have an $L$-shaped slit. The hands of $L$ are of equal length. Consider their $breadth<<length$. How will the Fraunhofer diffraction pattern corresponding to this slit look like?
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### Why is intensity of an electromagnetic wave independent of its frequency?

In electromagnetic theory, we define electromagnetic waves as two fluctuating electric and magnetic field which travel in a direction. We have a property called Poynting vector which is the power per ...
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### What is the physical meaning of frequency in the wave concept?

Treating light as a wave, we define its frequency. We see that light with different frequency have different colour. But, why? In wave, what property or physical meaning does frequency provide?
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### How to calculate Phase Difference in this question? [closed]

I have stumbled upon this question: Among two interfering monochromatic sources A is ahead of B in phase by 37°. If the observation is taken at point P such that PA - PB = λ/12 (λ is the wavelength of ...
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### Why do we sometimes use the entire particles energy and sometimes only the kinetic term to express a particles wavelength?

In the relativisitc case, the de Broglie wavelength formula can be derived in the following way: $$\gamma E_0=\hbar\omega=h\frac{c}{\lambda}\rightarrow\lambda=\frac{hc}{\gamma E_0}$$ In the classical ...
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### Which type of waves are matter? [duplicate]

Since all particles also show wave like nature. Do we know that which type of waves they are? I know they are matter waves but is it an electromagnetic or mechanical waves?
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### Phase of a wave in relativity

Take a one-dimensional plane wave $\exp(i(kx-\omega t))$. How can I show that its phase is a $Lorentz \ Invariant$? How to derive the form of $4-wavevector$?
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### Dispersive relation in quantum wave mechanics

Question 2. For nonrelativistic free particle $E=\frac{p^{2}}{2m}$ and using the de Broglie relations the corresponding dispersive relation becomes $$\omega(k)=\frac{\hbar k^{2}}{2m}$$ Then following ...
### Can a particle transcribing motion described as $y=(\sin x)^2$ be called to be in vibration? [closed]
I know that $\sin x$ or $\cos x$ curves can be said to be "in vibration," but what about $(\sin x)^2$?