# Tagged Questions

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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### Do all thermal radiators have the same surface brightness?

Imagine I heat a piece of metal to 1000K. It will be red hot and will emit black body radiation corresponding to this temperature. But what about the brightness? Assuming the bulk is opaque, does it ...
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### Hot Object In a Cooler Space [closed]

How would you calculate the heat given by an object that is hotter than its surroundings? I know there's Newton's Cooling Law, but what about any heat given off by radiation? Are these additive ...
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I'm wondering about the equivalent dose and the radiation weighting factor of photons (according to ICRP 103). Why is the weighting factor independent from the energy of the photons?
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### How do molecules absorb heat?

How do molecules absorb and retain heat, and how is that heat able to still affect nearby molecules? On Venus there is a green-house effect where the large, dense Carbon-Dioxide atmosphere absorbs ...
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### How can I estimate the number of X-Ray photons generated from a x ray tube?

I have this problem. I have an x ray tube of which I know the specific (kV, mA, anode material) and I have to estimate the number of X ray photons hitting the sensor after passing through air and ...
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### Radiation by an accelerated charge

An elastically bound electron vibrates in simple harmonic motion at frequency $\omega$ with amplitude $A\;.$ Find the average rate of loss of energy by radiation. So I think I can use Larmors ...
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### Understanding Vaidya metric and pure radiation stress-energy tensor

I am following Vaidya metric and how it is related to pure radiation from Wikipedia. But when it reaches the line where stress-energy tensor is equated to product of two four-vectors, I cannot follow ...
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### How does a gas emit radiation with temperature when it's particles motion are linear?

Particles in gas move faster with temperature in a linear motion (root mean velocity equation?) right? It explains increase in pressure and effusion proportional to temperature. Solids emit radiation ...
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### Effect of radiation pressure on Earths orbit in large timescales

I have seen some posts concerning the radiation pressure exerted by the Sun on Earths surface (Force on Earth due to Sun's radiation pressure). Though it is fairly small may it have a considerable ...
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### What is the difference between beta positive decay and proton decay?

Though beta positive decay's have been observed, in which a proton decays into a neutron, positron and an electron- neutrino; the why is it not the same as the exotic proton decay which is ...
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### How does mass affect the range of a nuclear particle?

Heavy particles such as protons and alpha particles of certain energy will lose all their energies in a definite distance in a medium, and this distance is called the range. The range is the distance ...
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I ask this question again in a simpler, shorter form. Maxwell's equations can be derived with Special relativity starting from the Coulomb's law. Therefore all the phenomena of classical ...
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### Radiation heat loss and reuse

When the human body lose radiation heat rays, is there a way we can pick it up and collect it? And then use it over again by fex. using a heat exchanger and a device that can emit them (rays) back out ...
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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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### 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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### 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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### 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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### 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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### 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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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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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 ...
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### 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. ...
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### 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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### 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 ...
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### 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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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 10^{...
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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 ...