All Questions
Tagged with electromagnetic-radiation energy
164
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4
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3k
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What happens to the energy not absorbed by a radio?
If a radio tunes to a specific frequency, where does the excess energy go? If one continues to hit the resonant frequency, shouldn't the wire begin to melt at some point from too much energy?
user24082
1
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3
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Why doesn't a stationary electron lose energy by radiating electric field (as per coulomb's law)?
If an electron in a universe constantly generates an electric field why does it not get annihilated ? I am confused because I read that an accelerating charge radiates and loses energy. So, why won't ...
- 555
1
vote
0
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Time reversed laser
Recently, I read an article on time reversed laser. I don't know why they call it a time reversed. I have a doubt that why they use two laser in the device. And what is an anti-laser?
The device ...
- 598
49
votes
8
answers
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Amplitude of an electromagnetic wave containing a single photon
Given a light pulse in vacuum containing a single photon with an energy $E=h\nu$, what is the peak value of the electric / magnetic field?
- 1,056
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2
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Painting wine botles [closed]
Yes, it's a physics related question. Read on.
I know from general knowledge that in order to produce a decent wine, you must keep it in a dark place. Therefore, from my knowledge of physics I guess ...
- 378
6
votes
2
answers
14k
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The energy of an electromagnetic wave
The intensity of an electromagnetic wave is only related to its amplitude $E^2$ and not its frequency. A photon has the same wavelength as the wave that's carrying it, and its energy is $h f$.
So ...
- 309
8
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3
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How much light is there in space and how heavy is it?
Our night sky is filled with stars. On a dark night a significant fraction of the sky is light. This light, we are told, has been in transit for many millions of years. There must therefore be quite a ...
- 219
2
votes
2
answers
618
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Does EM radiation (any, i.e. RF), or sound, radiate everywhere at once?
I am having trouble understanding electromagnetic radiation (or waves in general, be it EM or sound). If I have a 1 Watt speaker, is it infinitely divided and spread out so that everyone in every ...
- 23
7
votes
4
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How do laser rangefinders work when the object surface is not perpendicular to the laser beam?
I find the functioning of a laser rangefinder confusing.
The explanation usually goes like this: "you shine a laser beam onto the object, the laser beam gets reflected and gets back to the device and ...
- 831
12
votes
3
answers
6k
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Explain how (or if) a box full of photons would weigh more due to massless photons
I understand that mass-energy equivalence is often misinterpreted as saying that mass can be converted into energy and vice versa. The reality is that energy is always manifested as mass in some form,...
- 21.1k
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3
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Does opening or closing the window in a non-AC car in the summer affect how much heat is felt inside?
This will perhaps look like a very basic and trivial question. But I find it confusing. As an experience, when you are travelling in non-AC car in summer, have people felt if putting on or putting off ...
- 655
38
votes
4
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Redshifting of Light and the expansion of the universe
So I have learned in class that light can get red-shifted as it travels through space. As I understand it, space itself expands and stretches out the wavelength of the light. This results in the light ...
- 3,871
9
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3
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Can we transport energy over infinite distances through vacuum using light?
I know that light (or electromagnetic radiation in general) attenuates in intensity as the square of the distance it travels.
Why does it attenuate?
Are the photons being scattered by the medium ...
- 1,483
2
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6
answers
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What's the problem with solar energy?
What "breakthrough" from a theoretical point of view is needed for solar energy to become feasible energy alternative?
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