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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Proof of the inverse square law for a uniformly bright sphere

On page 8 of "Radiative processes in Astrophysics" by Rybicki and Lightman they have a proof that the flux of a uniform sphere is inversely proportional to the distance of the sphere from the ...
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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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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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Death by neutrinos - polonium go home

In Randall Munroe's What If? He is calculating the Lethal Neutrinos dose. If you observed a supernova from 1 AU away—and you somehow avoided being being incinerated, vaporized, and converted to ...
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What is the condition for accelerating charge to radiate?

I was always taught that any accelerating charge produces radiation, but I don't think this condition is sufficient condition. For instance, any free charge on Earth is accelerated due to Earth ...
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Absorption of radiation due to temperature

I was wondering if the temperature of an object affects the amount of radiation it absorbs. For example, if I have a box that is hotter, will it absorb more energy as compared to the same cooler box? ...
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One way insulation?

I know from basic physics lessons that a box painted black will absorb heat better than a box covered in tin foil. However a box covered in tin foil will lose heat slower than a black box. So what ...
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Why aren't betavoltaics and alphavoltaics batteries widely used?

Betavoltaic batteries are devices which creates electricity from beta radiation of a radioactive material. Alphavoltaics operate similarly, using alpha radiation. The concept was invented roughly 50 ...
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How can scintillation gamma-spectrometers work given that track length is different for different angles?

As far as I understand, the basic principle of gamma spectrometer is simple - gamma ray hits scintillator, it generates number of photons which roughly proportional to gamma ray energy. Then we need ...
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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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172 views

Mean stopping range of $\alpha$-particles in air

I did an experiment in university in which I determined how far $\alpha$-particles emmited from an $Am^{241}$ source penetrate into air. I want to compare my result to literature values but... I cant ...
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How does heat energy travel in space?

How does the heat energy from the Sun reach us on the Earth? Since the kinetic energy of an atom is the amount of heat energy and there is no matter in space, how does heat from the Sun reach us?
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1/r Counting Rate for Radiation Experiment

In an experiment performed in the lab, I want to justify that, when the width of the Geiger counter window is approximately the same size as the distance between the window and a mildly radioactive ...
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426 views

Inverse Square Law in Beta Radiation

Setup: A radioactive source is placed at alternating distances from a Geiger Counter. Counts per second for 10 different distances (each spaced 1 cm apart) were taken for preset times ranging from 200 ...
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218 views

Conservation of mass-energy and nuclear transmutation

This may just be beyond the grasp of the everyman, but I'm trying, and failing, to grasp how conservation of mass-energy works in cases of beta decay and electron capture. A neutron has a mass of one ...
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Nuclear decay information

I'm looking at some gamma spectroscopy calibration data, produced by a known source (semi known... the source was last calibrated 2006...) My question is, looking at for example ...
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Why are we not affected by the radiation of the radioactive decay going inside the Earth?

I was reading the question Why has Earth's core not become solid?, and one of the answers says that The core is heated by radioactive decays of Uranium-238, Uranium-235, Thorium-232, and ...
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Energy Equation

I am reading a book on radiation and the author, while developing the equation of radiation transfer provides two forms of the equation, the second incidentally being more general and useful that the ...
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Definition of isotropy of radiation and its consequences

I have encountered different notions of isotropy of radiation and I would like to know if they are the same and what the exact definition of isotropy is, if one exists. Let's take black body ...
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How do I build an alpha emitter?

I would like to build an alpha emitter. I suppose I had some vague idea of knocking the electrons off of some helium. But upon further examination the idea does strike me as...naive? My question is ...
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What is weak interaction? I need easy and short answer

What is weak interaction? I need easy and short answer. I can't understand the definition of weak force. Why is it so difficult? Bosons, Mesons, Fermions, parity etc. Why the fundamental force is ...
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Background radiation: radon vs potassium 40

In doing a little research into natural background radiation, I came upon a table from the National Council on Radiation Protection and Measurement (NCRP). It shows that inhaled radon gas is by far ...
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How to solve the Fukushima incident?

I am trying to find out if it is somehow possible to take all this nuclear material, put it in some type of gamma chamber or blast it with neutrons to change the uranium isotopes into something ...
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Can I excite an already unstable element for accelerated decay?

Say I had an unstable element ready to go through beta decay and I introduced it to high speed electrons: would this lessen the time needed for the product to go through beta decay?
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2 ways to generate electromagnetic wave

According to Maxwell's equations, accelerating charges emit electromagnetic radiation. According to Quantum physics, heating causes electromagnetic radiation too. These 2 radiations, are they ...
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Will the absorption of high energy gamma rays end up heating the absorping material?

By high energy I mean 100+ MeV gamma rays. I think that at this energy of photons, pair production is the dominating absorption process. So, as known, in pair production an electron and a positron ...
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Does halving the intensity of a gamma ray mean absorbing half its energy?

Say a 1 MeV gamma ray is shielded by 1 cm (halving thickness) of lead. Now, what does "havling the intensity" mean ? Like will the new gamma ray exit with energy of 0.5 MeV ? and by that we can say ...
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Is deep-space radiation greater in the Sun, or in the shadow of Earth?

http://space.stackexchange.com/questions/604/is-it-possible-to-get-pregnant-through-natural-means-in-space indicates cosmonauts are at risk of irradiation whilst in space. What little I know about ...
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Study of Black-body Radiation

Why did scientists study black body radiations from something as complicated as a hollow container rather than the radiation from something simple like a thin solid cylinder?
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Kirchhoff law of thermal radiation

Kirchhoff's law of thermal radiation states that for thermal equilibrium for a particular surface the monochromatic emissivity $\epsilon_{\lambda}$ equals the monochromatic absorptivity ...
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Is compton scattering only effective by x rayphotons and gamma ray photons

Can Compton scattering work with any other forms types of photons, and why was the the Compton Scattering experiment only done with x ray photons?
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How is the energy distributed in a proton-antiprotion annihilation?

I know the products of the annihilation, but I don't know how much energy each particle has or gets. For example I know that 1876 MeV is released for each annihilation. Now, this energy is distributed ...
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312 views

What is the halving thickness of diferent materials against high energy gamma rays?

By high energy gamma rays I mean 10+ MeV to 100 MeV. Is there a way to calculate it ? Also, at these high energies, do heavier elements like Lead for example still have the advantage over lighter ones ...
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Would matter-antimatter annihilation create a fireball or not?

There has been a long discussion between me and Anna V on if the products of the annihilation will really cause a fireball to form and we haven't settled it yet. Our point here is that gamma rays ...
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Would a matter-antimatter explosion cause fallout?

I know matter and antimatter annihilation release a lot of gamma rays which are considered ionizing radiation if I am not mistaken. But what if the explosion happened on the surface of the earth, ...
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Is there a way to increase photon energy by decreasing its wavelength?

Can I decrease a photon's wavelength by a medium or a vacuum? Are there other ways of decreasing the wavelength?
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What type of electromagnetic radiation strikes the Earth's surface the most?

If you can could you lists the types of light from the greatest amount to the least amount (Ex: Visible, Infrared, Violet).
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What is the shielding in nuclear reactors mainly against?

I have a little knowledge about ionizing radiation and I have been confused over why nuclear reactors need these massive shields. So, if I am not mistaken, Alpha and Beta radiation are not that ...
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Reflection, transmission, absorption…how to calculate them?

I was wondering whether there is an equation that enables me to calculate the reflection, transmission, absorption and polarization, when the electric field everywhere is given? Consider this: You ...
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Interaction of coherent X-rays with matter

If we could irradiate a metal or a plasma with a coherent beam of hard X-rays, would the main effect be an ordered oscillation of the electrons like with a classical EM wave, or "compton-style" ...
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Cherenkov radiation and K-40

I am thinking if it's possible to detect Cherenkov radiation in water caused by dissolved natural potassium (KOH) in it without using photo-multipliers. The main question is does 1 beta particle ...
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Alpha decay, why does it occur? [duplicate]

I was reading about alpha decay and why it happens. The strong force holds protons and neutrons together, but I don't get why does an atom emit helium nucleus when it has too many ...
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Why does positronium decay into 2 photons more often than into 3 photons?

I cannot find the answer to the above question. I know that para-positronium is created with a probability of $25\%$ and decays into 2 photons, while ortho-positronium is created with a probability ...
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Why were the fathers of quantum mechanics so sure radioactive decay was indeterministic?

The classic example of an indeterministic system is a radioactive isotope, e.g. the one that kills Schrödinger's cat. I get there are arguments against hidden variables in quantum mechanics, but how ...
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Trouble justifying calculation of force on a sphere due to radiation pressure

I know very little about electromagnetic waves and light in general so you are going to have to bear with me. I am attempting to calculate the force on a sphere in a plane wave of light where the ...
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Extreme heating by Sun on Earth- Can eggs be fried?

Will it be possible to fry eggs in Sahara desert by just keeping them under the sun? If so, then will the radiated eggs be any different? Or will we have to use the solar cooking concept to some ...
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Jupiter radiation belt: where >MeV particles comes from?

When I read some discussion about exploration of Jupiter moons, or possibility of life there, a common argument is high dose of radiation in Jupiter's radiation belt (several orders of magnitude ...
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The Observance of Electromagnetic Phenomena

As far as I've seen, E&M waves are sinusoidal. Our eyes observe these patterns and give us colors, but in a situation like such: Why do electrons emit radiation? There is still a wave, or at least ...
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Why do electrons emit radiation?

I know how you can emit light with an alternating current, running back and forth, creating an electric field in addition to the magnetic field. But why does an electron emit light when it gets ...
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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 ...