# Tag Info

7

What's wrong with this diagram (aside from the exaggerated angles)? Answer: Nothing, aside from the exaggerated angles. Let's try estimating the magnitude of the effect for dry air, which seems to be the focus of the question. According to ref 1, a good semi-empirical model for the index of refraction of dry air is  n = 1 + 10^{-6}\times\left(776.2+4.36\...

5

So we are only putting $mv^2/2$ energy which is gained by the wood but the extra output is current induced in the coil and magnet's motion, why is it not a violation to law of Conservation of energy? Actually, due to the magnetic radiation reaction force, the energy required in order to accelerate the magnet to $v$ is greater than $mv^2/2$. See https://en....

4

It does. It's called the Green Flash. There is also a much rarer alpine Blue Flash because blue light can survive at altitude:

4

Objects like your door do not "emit" any visible light. Instead they reflect the light that is coming from a lamp or the sun. If you put the door in total darkness it will be invisible to your eyes - unlike a piece of red-hot iron. Like all objects, the door does emit electromagnetic radiation as long as its temperature is above absolute zero. ...

3

It does so by reflection. Light containing all wavelengths (colors) of light falls upon the door surface, and the atoms and molecules there absorb certain of those wavelengths and reflect others. The reflected colors are what your eyes perceive.

2

Yes, it is correct that cold $H_2$ radiates much less electromagnetic radiation than other molecules (for example, carbon monoxide). Here's one way to think about this intuitively. On macroscopic scales, electromagnetic radiation is produced when charged objects accelerate. The atoms in a hydrogen molecule consist of charged particles (protons and ...

2

In reality M. Plank advanced first (constructed) a simple interpolation formula bridging two asymptotics - infrared and ultraviolet, both being well established experimentally. Then it turned out that his semi-empirical interpolation formula worked so well in different conditions that it seemed to be an exact formula. After that M. Plank tried to derive it &...

1

At the risk of giving an answer which is to complete, I'm going to offer interpretations for the indicated terms. Let me start by pointing out that the mathematical expression you are using describe the rotation of vectors in the complex number plane. This is convenient for dealing with phase differences, but we normally assume that only the real ...

1

We start with the Electromagnetic wave equations \begin{align} \nabla^2\mathbf E\boldsymbol{-} \dfrac{1}{c^2}\dfrac{\partial^2 \mathbf E}{\partial t^2}& \boldsymbol{=}\boldsymbol{0} \tag{01a}\label{01a}\\ \nabla^2\mathbf B\boldsymbol{-} \dfrac{1}{c^2}\dfrac{\partial^2 \mathbf B}{\partial t^2}& \boldsymbol{=}\boldsymbol{0} \tag{01b}\label{01b} \...

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