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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Light interference with light and other EM waves [duplicate]

Lets assume a room with one or two sources of light (normal light bulbs or fluorescent lamps). So if we look at lamp from any direction we see it. We also see different objects in the room because of ...
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55 views

Is there a gravitational radiation reaction force?

As you may know, the linearized relativity theory (or gravitoelectromagnetism), obeys equations analogous to Maxwell's equations in electrodynamics. These equations in ED result in the troubling ...
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Can alpha, beta or gamma radiations emitted by a radioactive substance be controlled? [duplicate]

Just saw this question in a school class 10 exam. Google search did not yield useful results. Can anyone please explain the answer here?
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51 views

How Much Does Roof Color Affect Energy Consumption?

I'm not sure whether this is off-topic; if so, I do apologize and will fully understand votes to close. That said: I live in a climate that's quite cold much of the year but gets pretty hot in the ...
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1answer
45 views

how is the state parameter determined?

For radiation, dark energy and dust the pressure and energy density are related, respectively, by: $p=\frac{1}{3}\rho$ $p=-\rho$ $p=0$ My question is why? How does one show that this is how ...
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44 views

Beta decay - Relative probability of electronic conversion for different disexcitations energies

I'm studying, experimentally, beta decay phenomena. Internal conversion of electrons happens when we have a sobreposition between a excited nucleus with it's electronic cloud. The colision between the ...
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47 views

Does adding static charge to a body increase its mass?

If a body becomes charged by losing electrons for example, it will experience a braking force when it is accelerated due to radiation called Bremsstrahlung radiation. Part of the energy used to ...
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0answers
196 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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Confusion about radioactivity

The following question is from General Problems on Physics by I.E Irodov 6.220. Find the decay constant and the mean lifetime of $^{55}\operatorname{Co}$ radionuclide if its activity is known to ...
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Maximum electron momentum in $\beta^-$-decay

This should be easy, but I think I have a mind-block... For $\beta^-$-decay, what is the maximum possible momentum for the electron? The two equations I can use are conservation of energy and ...
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1answer
13 views

Smart capsules for radioactive metals

If we add or remove an election to the atoms of radioactive metals, they will become the isotopes of their adjacent chemical elements in the periodic table. I ask the community whether the resulted ...
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0answers
18 views

Modeling total absorption using absorbance of multiple visual layers

I have a question involving light absorbance versus absorption. It applies to a stack of different photoreceptor types. I understand the difference between absorbance, which is basically equal to ...
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3answers
26 views

Measuring Activity

The formula for Activity of a radioactive substance is $ \frac{dN}{dt}=A=λN $. If we have an initial number $N(0)$ of some Radionuclide, which has a halflife of, say, 12 hours, is there any ...
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151 views

Model to convert radiation data from one tilted surface to a different one?

I have measuring data of global radiation on a tilted surface (a solar collector surface). Now I need to do 2 things: split the tilted global radiation into its diffuse and beam parts calculate ...
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3answers
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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 ...
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2answers
2k views

How to detect a secret nuclear detonation here on the earth?

How can we know that North Korea and Iran (to name a few) are exploding nuclear weapons if no inspectors have ever been granted access to suspected nuclear sites in these countries? How can we ...
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3answers
97 views

Can a single particle be “heated” by radiation?

From the point of view of statistical thermodynamics, a single particle doesn't have a phase (state of matter), nor temperature. What would happen if heat is transported to this single particle via ...
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1answer
69 views

Determination of radiation pressure

Consider the incidence of an electromagnetic wave on the plane $x=0$. We have that: $$f_x=\frac{dF}{dV}$$ $f_x$ is the volumic force density on the medium. My doubt is purely mathematical. I ...
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1answer
291 views

Why does a damped quantum harmonic oscillator have the same decay rate as the equivalent classical system?

$\newcommand{ket}[1]{|#1\rangle} \newcommand{bbraket}[3]{\langle #1 | #2 | #3 \rangle}$ Why does the decay rate for a damped quantum harmonic oscillator exactly match the classical limit? Background ...
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6answers
687 views

Confusion about Length Contraction (ex in Muon decay)

I am a bit confused about the implications of length contractions; For example, in the muon decay problem, we assume that the distance between the muon and the earth is contracted only in the frame ...
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0answers
31 views

Question on decay constant

I have a model of the radioactivity of a target which is undergoing Neutron Spallation. The Protons are incident upon the target for approximately 200 hours. Within the model, over the course of ...
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1answer
48 views

Is (or why isn't) static charge as lethal as ionizing radiation?

Ionizing radiation, e.g. the "stuff" emitted by radioactive materials, is dangerous to humans since changes to the electron configurations (in the human body) causes the various molecules (in the ...
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3answers
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Is the direction of gamma-ray emission by a nucleus totally random?

Let's consider an excited nucleus emitting one gamma-ray (not cascade etc). Is the direction of gamma-ray emission completely random? In other words, is the probability to detect this gamma equal for ...
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1answer
62 views

How does a photon raise the temperature of a gas?

The temperature of a fixed volume of a gas is increased when it interacts with radiation. Why does the temperature increase (i.e. why does the velocity of a gas molecule increase) when a photon is ...
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2answers
3k views

Would a laser with four possible energy levels be better than three?

I'm wondering about achieving population inversion for a laser. I learned that without an active medium, it's not possible to create a laser with only two energy levels, but it would be possible with ...
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3answers
1k views

If UV radiation 1 cm away from the halogen bulb is equal to Sun's radiation, what is the level of radiation 1 meter away?

Halogen light bulbs emit some amount of UV radiation, and some sources consider them dangerous. Here it is written, that UV radiation (of certain types) from a particular halogen bulb was equal to the ...
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2answers
114 views

beta minus decay: expression for maximum electron energy

I'm having some trouble finding an expression for the maximum electron energy in beta minus decay. In the frame where the neutron is initially at rest, conservation of momentum reads: ...
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1answer
48 views

How can a string vibrating in a plane radiate sound?

If a plucked guitar string vibrates in a plane, how are waves produced that travel in all directions? I'd have thought that a vibrating string can only produce waves in its plane of motion.
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21 views

Why doesn't the formula for the Einstein coeff contain a radius?

I am trying to understand the Einstein coefficients and using the formula found on wikipedia ,the coefficient for spontaneous emission is equal to (emission coeff * 4*pi)/(hfn2) (first formula on ...
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1answer
40 views

Method used to prove emissive power, $E \propto T^4$

Stefan's Law states that emissive power($E$) of a black body is proportional to $T^4$. But how did Stefan arrive at the conclusion? I mean, it is not possible currently to get a perfectly black body, ...
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0answers
37 views

wave propagation (refractive index gradient) [closed]

I have 2 questions and need some advice from you all. A $30\,\mathrm{km}$ microwave link operates at $4\,\mathrm{Ghz}$ using $4\,\mathrm{m}$ parabolic reflector antennas. the transmit antenna is ...
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4answers
362 views

Radioactive decay - What mechanism decides when an unstable nucleus decays?

My first question on Stackexchange (if it is formatted wrong or something please tell me so I know in future) - here it is: Given an unstable nucleus (exactly which nucleus is not particularly ...
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1answer
85 views

What happens to mass during beta decay?

Sorry for being ignorant, but I'm in high school and our chemistry teacher barely went over beta decay. I decided to do some research and learned that in β+ decay, positrons are emitted from protons ...
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2answers
717 views

How to interpret Stefan-Boltzmann's law?

The Stefan-Boltzmann equation states $e=\sigma T^4$, but how do we interpret this? Is this completely wrong: A body of size $s^2$ generates the radiation/temperature $T^4$ for a given size and a ...
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2answers
123 views

What would be the dose rate of 109 grams of uranium per day/year?

I know that with a Pancake probe that can read alpha you can get up to 30K CPM on a small plate. I ordered a 6" red plate off ebay and measured outside the box when it came in. It registered around ...
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0answers
37 views

signal from uniformly moving charge

As a charge moves, its field changes, and this change can only be propagated outward at the speed of light. Thus the field lines will be curves that keep changing apparent source point and direction. ...
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1answer
88 views

Meaning of angles on Feynman diagram

In physics class, I am currently studying Feynman diagrams. We are taught the basics like conservation of charge and the direction of time but the examples in my book all seem to follow specific paths ...
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16 views

How do amorphous objects emit blackbody/thermal radiation? [duplicate]

How do amorphous objects emit blackbody/thermal radiation when such objects don't have optical phonons?
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1answer
90 views

Can a sample of beta radiation be considered as the fabled philosophers stone? [closed]

Given that it is possible to produce gold in nuclear reactors (even if not economical), is there a natural source of beta radiation whose half life is similar to that of human lifetime and whose beta ...
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1answer
33 views

Order of emission of radioactive particles

Is there any sort of sequence in the emission of radioactive particles? ie. alpha, beta, gamma or any other type of decay I don't know about. Specifically, I wanted to know is there any evidence to ...
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1answer
137 views

What is the difference between zero background radiation and field background radiation in Nuclear Physics measurements?

Can someone please explain the difference between these two terms (Zero Background Radiation and Field Background Radiation) used in radiometric prospecting measurements?
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2answers
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How is the Earth heated by a Full Moon?

While the moon is certainly not a good reflector of solar radiation, surely the radiation it reflects back heats the Earth (even if it is a terribly small amount). How would one go about calculating ...
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1answer
20 views

How does an object in vacuum loose its temperature? [duplicate]

Well, it radiates in the infrared, I guess. But how exactly are these photons created? The atoms have some kinetic energy, which makes up the temperature. So while the atoms or molecules jitter a bit ...
2
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0answers
37 views

Is there an orbit decay associated with synchrotron radiation of a relativistic particle?

I had a question about a particle (say a proton) with relativistic energies interacts with a magnetic field (in the z direction). As it is accelerates the particle emits synchrotron radiation. ...
3
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1answer
22 views

Models for populations of decay products

I'm looking to create a population model for the specific nuclides in a neutron spallation source. The source is a target (Tantalum clad Tungsten) which is being bombarded with protons, and in turn is ...
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1answer
31 views

Notation on chart of the isotopes

I recently purchased a complete chart of the isotopes, (this one: https://shop.marktdienste.de/shoppages/produktuebersicht.aspx ) and have it on the wall next to me in work. The different coloured ...
8
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2answers
709 views

Do human bodies give off a consistent but unique radiation/electromagnetic/energy signature?

Is there any facet of the energy emitted by a human body that is consistent and unique - like a fingerprint, but a signal that could be detected by a remote device?
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1answer
83 views

How much radiation does the Earth receive from the Sun's total radiation? [closed]

I was thinking how to solve this problem. $1\,\mathrm{AU}$ is roughly the distance from the Earth to the Sun, $1.4960 \times 10^{11}\,\mathrm{m}$. The radius of Earth is approximately $6.4 \times ...
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1answer
53 views

Bismuth vs tungsten shielding

When shielding 1250-keV $^{60}$Co at a nuclear facility, are there instances in which a shield produced of a mixture of bismuth and silicon can provide higher/equal attenuation than a shield produced ...
2
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1answer
29 views

Radioisotope beta decay generator

Why are there no electrical generators utilising the electron/s of beta decay from a radioisotope for generating a working current? For example, how much radioisotope would I need to generate 1A or ...