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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216 views
Reconstruction of information stored in an evaporating black hole from the emission spectrum?
For simple setups, where the radiation field deviates not too far from thermodynamic equilibrium (< 10 %), corrections to the Planckian thermal emission spectrum can be calculated (and measured) ...
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2answers
266 views
Do and can phone signals come inside AC car which is glass-packed
Can phone signals penetrate glass, so can I expect phone signals to come if I am sitting inside a closed AC car.
Thanks,
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2answers
225 views
Is it possible to speed up radioactive decay rates? [duplicate]
Possible Duplicate:
Do some half-lives change over time?
Would it be possible to considerably speed up the decay rate of an isotope?
Considerably meaning more then a 1 or 2% increase in ...
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1answer
56 views
Does it happen at high energies (heavier leptons decay)?
A lepton is an elementary particle. The best known of all leptons is the electron which governs nearly all of chemistry as it is found in atoms and is directly tied to all chemical properties.
The ...
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3answers
142 views
Is it true that an isolated fundamental particle does not decay?
Is it true that an isolated fundamental/elementary particle does not decay?
It seems logical to me.
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1answer
224 views
How is tritium illumination possible without negative health effects?
Turns out there's tritium illumination - a tiny very strong plastic tube will be covered in phosphor and filled with tritium. Tritium will undergo beta decay and a flow of electrons will cause the ...
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2answers
128 views
How is a cathode ray tube different from beta minus radiation?
In beta minus the result is one neutron in the nucleus changing to a proton, plus an electron and an anti-neutrino being sent off.
The antineutrino is indifferent to our health. So I guess what ...
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2answers
86 views
Can there be energy with no force or energy with no power?
I think that both force (number of newtons) and power (p=ui(?)) implies that there is energy so we can't have force without energy and we can't have power without energy(?)
But can there be energy ...
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1answer
44 views
effects of sunlight through a glass window?
Both my father and my grandfather where drivers, and over time ended up with a wrinklier left hand compared to the right hand, due to sunlight exposure over 40+ years while holding the steering wheel ...
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1answer
67 views
What is the relation between surface area and radiation, if any?
Basically I wonder what happens to emitted radiation by douubling a light e.g. twice the surface area of the sun will emit how much more radiation? 4 times more? Is there a formula?
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1answer
110 views
How to choose a $\alpha$, $\beta$, $\gamma$ measurement detector?
There are many different detectors for different radiation,such as NaI,HpGe,CsI for $\gamma$ detection,and ionization chamber,proportional counter,Geiger counter for $\alpha$, $\beta$ detection,but ...
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1answer
69 views
At what rate does radiation exposure occur at high-c speeds?
If a future astronaut travelled to Alpha Centauri at a significant percentage of light-speed?
Apart from increased blue shifted radiation from their direction of travel - how would they experience ...
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1answer
99 views
Radiative transfer equation solution
The solution of the radiative transfer equation for spherical ionized blob :
\begin{equation}
\frac{dI_{\nu}}{ds} = j_{\nu}-\alpha I_{\nu}
\end{equation}
and solution is (Ref: ...
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1answer
1k views
Why are umbrellas black?
Why are umbrellas specifically in black? Of course we do have colored ones, but black is the majority. Is there any scientific reason behind it?
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0answers
39 views
Find mass of Plutonium in alpha decay [closed]
I did:
$$\Delta mc^2 = (m_{Pu}+m_{U}+m_{He})c^2$$
$$\frac{5.24 \times 10^6 eV}{(3 \times 10^8)^2} = m_{Pu} + 235.043924 + 4.002603$$
$$m_{Pu} = 239.0465$$
But answer is 239.052157, slightly ...
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1answer
53 views
Computing $\Delta m$ in $\beta^-$ decay
$\require{mhchem}$What is the energy $Q$ released when $\ce{^131_53I}$ decays and $\ce{^131_54 Xe}$ is formed? The atomic mass of $\ce{I}$ is $130.906118~u$ and the atomic mass of $\ce{Xe}$ is ...
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0answers
23 views
Probability in Radiation Physics for electrons [closed]
The total linear attenuation coefficient for 10-keV electrons in water is 77.6 μm^-1, partitioned as follows:
Elastic scattering 38.2 μm^-1
Ionization 37.4
...
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0answers
50 views
Temperature of an Object in Space [closed]
Rotating cylinder in space
Hi all
I've been having problems trying to calculate the temperature of an object in space, and was hoping I could get some help. Say we have a cylinder in space rotating ...
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0answers
98 views
Calculating the Heat Losses of Convection and Radiation [closed]
A water pipe for central heating with length $L=10m$ and diameter $25 mm$ is running over a cold attic with $T_{air} = 278 K$. The radiation temperature of the surroundings is usually lower than the ...
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0answers
70 views
Beta decay for Ar-38, K-38, Cl-38
I want to prove that $^{38}Ar$ is stable with respect to $\beta$ decay, that $^{38}Cl$ decays by $\beta^-$ and that $^{38}K$ decays by $\beta^+$.
I know from Googling that this is true, and I also ...
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0answers
49 views
Radiation question [closed]
I am having some trouble with the following question
Sam is seeping into a room from the basement at a rate of
$$\frac{1}{6} \times 10^6 \frac{\mathrm{pCi}}{\mathrm{hr}}$$
(pCi=picocuries). The ...
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0answers
37 views
Non reflecting boundaries in waveguides
Can someone please explain the Sommerfeld radiation condition and what is the alternative non-reflecting boundary conditions for waveguides of general geometries?
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0answers
77 views
The Deflecting System in a Hot Cathode Ray Tube
In an HCR-Tube, the deflecting system used to deviate the electron beam is made of positively charged plates. How is this justified? If, due to some malfunction, the electron beam deflects from its ...
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0answers
57 views
Which of the following radiation measurement devices is suitable to measure the radiation level in a Data Center? [closed]
Which of the following radiation measurement devices is suitable to measure the radiation level in a Data Centre?
Geiger Mueller (GM) Detectors with Pancake Probes
Alpha Radiation Survey Meter
...
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0answers
18 views
Is there a way to compute or explain if a decay prefers decaying into mainly mass or mainly energy?
Is there a way to compute or explain if a decay prefers decaying into mainly mass or mainly energy ?
I know quarks prefer to decay into the most massfull quarks : ...
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0answers
48 views
What sort of thin film experiments can be done in zero gravity and in the presence of cosmic radiation?
I recently found out about sending stuff into space and using the unique zero gravity and cosmic radiation riddled environment to investigate stuff like crystal growth. Since thin film science is a ...
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0answers
49 views
Problem on nuclear physics radioactivity [duplicate]
Possible Duplicate:
How do we know that C14 decay is exponential and not linear?
Please help me solving this problem.
Find the half life period of uranium-238,if one gram of it emits ...
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0answers
43 views
radioactive decay in molecular constituents [duplicate]
Possible Duplicate:
What happens to chemical compunds that include radioactive nuclei, when those decay?
Suppose a radioactive atom, which is incorporated in a molecule, decays? What ...
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1answer
124 views
Radiation dosage problem [closed]
A large room is filled with air polluted with Caesium-137 at an average density of 1 Cs-137 particle per $\text{cm}^3$. A human is sitting inside the room for duration of $T$. What is the total energy ...
-1
votes
1answer
101 views
Determining energy of gamma-rays after alpha-decay of Am-241
So it turns into Np, and electrons just falling into 'free new' levels and emmiting, right?
Give me a link where to read, please, if it's very easy to answer.
-2
votes
3answers
365 views
Why did people expect the number of electrons emitted because of the photoelectric effect to rise with the radiation's intensity?
The number of electrons emitted because of the photoelectric effect
rises with the frequency of the radiation
is not influenced by the intensity of the radiation (As Chad points out, this is wrong, ...
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votes
2answers
301 views
Transient radiation--heating a slab
Hey guys I really need help on this problem.
A ceramic slab of dimentions 5cm x 10 cm x .25 cm has to be heated to $177\,^{\circ}{\rm C}$. The ceramic slab travels on a conveyor belt traveling at ...
