Radiation is a process in which energetic particles or energetic waves travel through a medium or space. The particles or waves radiate (i.e., travel outward in all directions) from a source.

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Is the plasma state always visible?

All the examples of plasma I have come across are visible. Is there any plasma which is not visible? For example, during a dark lightening we don't see the radiation because its gamma radiation. Is ...
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1answer
18 views

What is the distribution of energy between the alpha, beta and gamma particles emitted in nuclear fallout per one RAD?

I have been trying to find a relation to be able to convert from RAD to REM. What I found is that I need to know the "quality factor" as some sources call it, which is the effect of different ionizing ...
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1answer
37 views

internal conversion and the electromagnetic force

I have read that the mechanism behind internal conversion, in which a nuclear transition leads to the ejection of an electron in one of the lower atomic orbitals, is related to the fact that the ...
3
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1answer
64 views

Radiation emission and absorption

Any object can emit and absorb radiation and the power of emission can be represented by the Stefan-Boltzmann law: $$P=A\epsilon\sigma T^4$$ In many texts the net power radiated is the difference ...
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1answer
1k views

Finding electric power generated using heat transfer

I'm working through an example I have been given to study. Suppose I have a 2m X 4m photovoltaic panel on my roof that is irradiated with a solar flux of $G_s = 700W/m^2$. Given: $\alpha_s = 0.83$ ...
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How does radiation shielding using absorbing materials work?

I understand that, for example, a thick enough sheet of lead can absorb gamma radiation, but I want to understand what actually happens at the molecular/atomic/subatomic level. Also, can the same ...
44
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3answers
25k views

Why can Hiroshima be inhabited when Chernobyl cannot?

There was an atomic bomb dropped in Hiroshima, but today there are residents in Hiroshima. However, in Chernobyl, where there was a nuclear reactor meltdown, there are no residents living today (or ...
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1answer
49 views

What can make signal triangulation tricky?

Usually, when you're trying to find a source of whatever signal, you move around the source and then calculate the position using triangulation. I'm specifically talking about low frequency signals, ...
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1answer
47 views

Could airport security devices detect differences between printed and written documents?

If airport security scanners of any kind (xray, thermal, whatever else they use) looked at two items: A printed paper textbook The same printed paper textbook into which we have inserted a regular ...
4
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1answer
130 views

Does any lower frequency electromagnetic radiation naturally reach us from the Sun?

I am not sure whether the sun originally emits everything in the electromagnetic spectrum, (whatever the relative strengths of each portion might be), but I do read that many waves, including gamma / ...
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1answer
245 views

What exactly is the composition of radiation in interplanetary space?

The articles I found on radiation in the solar system mostly dealt with solar wind, I wonder about other types. Is there a breakdown that tells me, withhin an order of magnitude, at least what ...
3
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2answers
269 views

Why doesn't a nuclear fuel pool become irradiated?

Why doesn't the volume of water in a nuclear fuel pool become irradiated? Why wouldn't the water around the pool become radioactive and circulate around making the whole thing deadly? My question ...
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59 views

Optically thick media

What does "optically thick media" mean? Does this property depend on the length of an enclosure? Why is the diffusion approximation for the radiative transfer equation applied to optically thick ...
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2answers
345 views

How can blackbody radition be explained by quantization?

I don't understand why quantization makes a peak on the blackbody radiation curve (so there is no UV catastrophe) and the relationship between that peak and quantization concept. When the blackbody ...
5
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2answers
91 views

Why is the spectrum of the $\beta$-decay continuous?

the spectrum of the Gamma and Alpha decays are both discrete, i.e. the $\alpha$-particles and the $\gamma$-rays take on only discrete values when emitted from a decaying nucleus. Why is it then, that ...
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1answer
34 views

Is it possible to generate electric energy from the radiation of radioactive materials

I wonder if it is possible to generate electric energy from the radiation of radioactive materials like nuclear waste? If it is then wouldn't that also mean that it could be used as an energy source ...
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1answer
32 views

Frequency-averaged (gray) radiative transfer

The equation for radiative transfer is $$ \omega \cdot \nabla I = \kappa(B - I) $$ where $I$ is the intensity of radiation, $\omega$ is the ray direction, $\kappa$ the absorption coefficient, $B$ the ...
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how safe is using the remote car toy from radiation

how safe is using the remote car toy from radiation, especially for kids, The manufacturers claiming that it will be safe, but is that 100 % safe over kids
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1answer
32 views

Absorption cross section and absorption coefficient

What is the absorption cross section, how is it measured? How to convert it to the absorption coefficient (measured in cm$^{-1}$)?
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0answers
31 views

Absorption coefficient from HITEMP or HITRAN [closed]

How to calculate the absorption coefficient (for radiation) from HITEMP or HITRAN databases? Or where can I find some tables or plots for the absorption coefficient?
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2answers
110 views

Does blackbody radiation work like this?

In a blackbody object the photons are reflected back and forward. If I heat up the the blackbody object with microwaves or other types of photons the electrons in the wall would vibrate. When the ...
3
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3answers
463 views

Would being underwater help survive a nuclear bomb?

If I jump in my pool, on the river near my house knowing that a nuclear bomb, or atomic or H-Bomb exploded around 10 km from my house, would I survive? The way I see it is that water will protect me ...
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2answers
51 views

Measurement of heat in electrons

Is there any method to measure the heat of an electron and if there is; then is it a constant or a variable.
2
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2answers
85 views

Why do I get readings from my radiation meter with magnetized pieces?

What causes those radiation readings in my radiation meter (See the linked video)? Metal pieces were magnetized. Used radiation detector is RADEX RD1503. "Radiation" is not generated if the tube has ...
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Would wearing clothing that is black on the inside and white on the outside keep you cooler?

The Straight Dope ran an explanation of why nomads often wear black clothing - it absorbs heat better from the body. On the other hand, white clothing reflects sunlight better. Is it possible to get ...
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1answer
82 views

Per unit of energy, what radiation is the most penetrating?

This question about nuclear reactor shielding got me wondering, what forms of radiation are the hardest to shield? I suppose Neutrinos will have to be excluded since they're the obvious winner. So ...
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3answers
132 views

Acceleration of electric charges and radiation

According to classical electromagnetic theory, accelerated charges should emit radiation and lose energy. The reason given in my book why atoms don't emit radiation (say, when the atom moves along a ...
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0answers
155 views

Is WiFi safe for humans? [closed]

I have wifi on at my home almost all the time. I learned that the frequency of visible light is around several hundreds of THz, while the frequency of wifi is only several GHz, which is only ...
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1answer
32 views

Explanation of binding energy in decays

Everyone knows that the mass of a system is less than the mass of its components, with the equation: $M = \sum_i m_i - BE(M) $ Now, if we consider a general decay, lets say $A \rightarrow \sum_i ...
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1answer
6k views

What common materials can effectively block infrared radiation?

I have a plastic container and want to make sure that infrared radiation (specifically, in the 750-850 nanometer range) cannot pass through it. Would wrapping it in aluminum foil do the trick? If not, ...
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2answers
43 views

How does gamma ray emission make an atom more stable? [duplicate]

One of the types of radioactive emissions is gamma emission. I understand how the other two types, alpha and beta, help to make the atom more stable. How exactly does gamma emission help to make the ...
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0answers
18 views

Why is relative biological effectiveness of photon and electron the same ?

I was wondering, why seemingly two distinct particles have the same RBE (relative biological effectiveness) ? Would the charge of electron not do more/less damage ? While on the subject, does anyone ...
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4answers
531 views

Can we say there are 2 EM radiation types?

EM radiation seems to come from two different sources: According to the Maxwell, by acceleration of electrons According to the Bohr, by jumping of electrons between energy levels? Are these two, ...
6
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2answers
64 views

Why do $\beta$ particles not get attracted to the nucleus?

I currently have a very limited knowledge of how radiation works etc, but while sat in class the other day, one question occurred to me that even my teacher could not answer. We have been learning ...
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3answers
55 views

Why do grey body radiators not heat up?

So I'm doing so work on the earth's climate system, and modelling it as a grey body radiators, and I've come across the phrase: "$62\%$ of the outgoing energy is lost to space and the other $32\%$ is ...
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1answer
27 views

Increasing Earth's albedo

How much of a difference would it make if every roof, road and vehicle were painted white? This would certainly reduce the urban heat island effect but how much of a difference would it make to total ...
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3answers
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Tritium decay is spontaneous even if the binding energy of tritium is higher than the binding energy of 3He. Why?

Given this nuclear reaction: $^3_1\mathrm H\to {}^3_2\mathrm{He}+e^-+\bar{\nu}$ and knowing the binding energies: $BE(^3_1\mathrm H)=8.48 \,\mathrm{MeV}$ $BE(^3_2\mathrm{He})=7.72 \,\mathrm{MeV}$ ...
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1answer
58 views

Observation of light bending spacetime [duplicate]

Has radiation or energy bending spacetime ever been observed? If not, is it likely that it ever will, assuming current technology? Note: This is not a question of space bending light, but of light ...
2
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1answer
54 views

Deriving Rabi rotation matrix

I want to understand where the matrix: $$ \left|\psi(t)\right> = \binom{a(t)}{b(t)} = \begin{bmatrix} cos(\Omega t/2)&-ie^{i\phi_L t}sin(\Omega t/2) \\ -ie^{-i\phi_L t}sin(\Omega t/2) & ...
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3answers
203 views

Any real life demonstrations of radioactive decay? [duplicate]

I'm skeptical about a lot of things in physics, but I have a great interest in it and I'm studying it in college next year. However I am very skeptical about some things. I find that for physics, it ...
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4answers
102 views

Can nuclear transmutation be observed in real time?

Ignoring the quantum zeno effect (if possible?), can we observe in real-time the transformation of one element to another? I'm talking about an amount visible to the naked eye where one could see ...
2
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1answer
164 views

When (Exactly) Does Bremsstrahlung Radiation Occur?

Regarding the Bremsstrahlung Radiation emitted when a charged particle curves inside a uniform magnetic field; Is there a way of calculating the angle through which the charged particle will precess ...
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Question: if a nuclear reactor of a submarine explodes will it contaminate the surrounding waters? [closed]

After watching a Naval War movie I began to ask myself this question and I would like to know.
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3answers
349 views

How to detect Iodine 131?

$I_{131}\rightarrow \beta \text{ 333.8 KeV(7.27%)}\rightarrow \gamma\text{ 636.989 KeV(7.17%)}$ $I_{131}\rightarrow\beta\text{ 606.3KeV(89.9%)}\rightarrow\gamma\text{ 364.489KeV(81.7%)}$ (you can ...
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4answers
185 views

Do photons make the universe expand?

I have a problem understanding the ideas behind a basic assumption of cosmology. The Friedmann equations follow from Newtonian mechanics and conservation of Energy-momentum $(E_{kin}+E_{pot}=E_{tot})$ ...
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1answer
33 views

X-ray production rate [closed]

A 100 MeV proton beam of $10^{14}$ proton/s is perpendicularly incident on a rhodium foil 25 $\mu$m in thickness. Estimate the production rate of K and L x-rays(use the figure below). So far I ...
2
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4answers
132 views

Detecting radiation from tritium keychain

I am measuring radiation from 6 tritium glow keychains. Usual gamma detector does not detect anything (this is expected), but on beta detector with thin window I am getting about 5 counts per second. ...
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1answer
76 views

Physics and Skin Color: What differences do physicists observe between different skin colors?

I majored in social sciences, so I haven't taken a science class since 1999, so forgive me if I don't ask this right. What difference would skin color make from a physics perspective? Would there be ...
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37 views

How to measure the wavelengths of ultraviolet lines in the hydrogen spectrum?

how to measure the wavelengths of ultraviolet radiation isn't it invisible? it's possible to measure visible radiation but how to measure invisible radiation?
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58 views

Rutherford alpha scattering?

From Rutherfords alpha scattering, where alpha where fired at a thin peace of metal foil, he concluded that the nuclie was positivly charged. He made this conclution from the fact that alpha particles ...