Radiation Definition and 1000 Threads

A radiation increase of isotopes commonly associated with nuclear power production has been detected in Northern Europe in the past few weeks:

Here is something that struck a note to me, they give the CMB radiation in it's frequency which is in Ghz as the name "microwave" implies and then they also give a temperature in Kelvin. But how can light aka EM radiation have a temperature? I thought only matter with mass can have a temperature...

Some site I've looked at are https://www.sciencedaily.com/releases/2000/10/001016073704.htm and [Link to garbage site removed]

Hi All In discussing another issue it occurred to me the only experiential evidence I know that normal visible light is EM radiation is Faraday Rotation. I strongly suspect we have a lot more these days. Amusing story. Fermi's wife had a degree in general science that did not cover...

What percentage of the universe’s A) total mass —including dark matter— and B) radiation energy is estimated to reside in: Inter-galactic space covering i) inter-galactic medium and ii) distinct inter-galactic astronomical objects; and Galaxies covering iii) inter-stellar gas clouds, iv) stars...

Hi, the approximate (not accounting for plate size and separation distance) formula for heat flux exchanged via radiation between two parallel plates is: $$q=\frac{\sigma (T_{1}^{4}-T_{2}^{4})}{\frac{1}{\varepsilon_{1}}+\frac{1}{\varepsilon_{2}}-1}$$ where: ##\sigma## - Stefan-Boltzmann...

Figure from Jackson, the ##0## subscripts indicate incident waves whereas the lack of subscripts indicate the scattered wave. Figure from Zangwill, the hat ##\hat{e}## vectors are for the incident electric field. We are dealing with unpolarized light so we have two orthogonal polarization...

Hello! I’m currently in the process of earning my bachelors of science in radiation therapy. I plan to get my masters in dosimetry, but I was wondering if anyone know if it was possible for a medical dosimetrist to advance their career by earning their PhD in medical physics. Essentially, I’m...

Hi, Source: https://en.wikipedia.org/wiki/Second#"Atomic"_second How were such huge number of periods per second measured originally? Was an instrument such as Michelson interferometer used? I think it was Albert Michelson who invented the interferometer to make calculations of wavelength and...

Hallo, can anybody help me and check if i have the right result: What is the minimum power P that a point source of radiation (I=8*10^(-7) W/m^2) at a distance of l=10 m from the listener must have in order to still be perceived? (Note: The emitted energy per area can be related to a spherical...

I am grateful for anyone for their time to answer this question. Some theories predict black holes will evaporate and eventually disappear. From my limited understanding, Hawking's theory predicts that quantum effects near the event horizon of a black hole are responsible for blackbody...

Hi guys, I am confused about the heat transfer mode of between two contacting material, especially in a channel flow. Obviously, conduction or convection dominate the heat transfer process in the process with low object temperature . But I am not sure if I have a fluid of 500 Kelvin, flowing...

https://www.thegreenjournal.com/article/S0167-8140(20)30185-7/fulltext What's the relevant science here ? Would just like to hear a bit more as to whether it holds out any meaningful prospects for treatment of Covid 19.

I've come across this alternative formulation of Planck's Law which links the number density to energy gap n(E) = \frac{2\pi}{c^2 h^3} \frac{E^2}{exp\big(\frac{E-\mu}{k_BT})-1} I've tried visualising this relation and I imagine it will look similar to the spectral density relation but I'm just...

The intensity is proportional to the square of the distance between the source and the body and also depends on the angle of incident. I = The intensity at 0° (Assuming I = some constant) then I0 = I cos(Theta) Theta = the angle of incidence. I want to solve this using trignomentry. Is it...

I have two bodies, one at a higher temperature say 1000°C (Body A) and the other is at 22°C (Body B). Body A emits Radiation (Surface to Surface interaction). The temperature of Body A is maintained by a constant supply of Energy. The Body B will absorb the Radiation Energy from Body A, and its...

Can water simply absord the kinetic energy from colliding air molucules to change its phase? And can water transformed into ice simply have the kinetic energy of its molecules increased to balance out the lost latent heat? Would not this again change ice into water?

I have two more questions:- (1) Can we calculate the time it takes specifically for water to radiate all its heat? (2) Heat is illustrated as kinetic energy of molecules, so why collision between particles should result in the conversion of kinetic energy into radiation. Why conservation of...

I cannot find a source of uranium glass beads/wands for art making. It is mentioned online that one can make UV glass with a derivative of uranyl nitrate, UO2(NO3)2 . Does anyone know a source of uranyl nitrate, or raw glass material, and what are the minimum safety protocols, such as...

For a body at temperature T, the radiative energy per unit area E depends on 4th power of T. I can obtain expression for specific heat c by differentiating Stefan's law with respect to T. Would it be the correct way of approaching this problem? Or do I need to employ certain models from Solid...

Let r = position of the electron = 6mm - 36.8μm; λ = mean free path traversed. Integrate E(r) = Q/(2πϵLr) between the two shells gives: V = [Q/(2πϵL)]*log(r/(r-λ)) I know that the question is asking for the voltage at which the electron energy will get to 23eV, but i am unsure how to get rid...

In electromagnetic radiation, the electric field and the magnetic field mutually induce each other: but my impression is that it would be better to say that they are two aspects of the same wave, so that there is no time between them. However, an alternative would be that there would be that...

I have tried to use the above equation. P2/64=(189/102)^4 P2=754.4431 But I don't know why the answer is wrong. Please help!

Hi, So there is already a written solution which I have, but this is more a question about why we omit reflection that come back to the same mirror? Method: Let us consider one of the mirrors, we know it will emit a heat flux given by: q_{1} = \epsilon_{1} \sigma T_{1}^4 . Given that we are...

As I understand it, it is the magnetic part of electromagnetic radiation which creates a current (AC) in a radio receiver (i.e in an antenna) which can be translated into sound/graphics and so on. Is this correct? I mean in the sense that it is the magnetic field in the incoming radiation which...

cos(theta)=c/vn cos(1.2 degrees)=((3*10^8)/v(1.03)) v=291262135.9 v/c=.971 so the particle is moving at (.971)c But mastering physics tells me this is wrong, and says that I'm not account for the angle. I am really stumped.

If we take the perspective that black holes thermalize (reach maximum entropy) in a very short time and then just sit there and grow in complexity, how do we interpret Hawking radiation in this picture? i.e. you can't just have the state of the black hole keep growing in complexity forever...

Hello, I'm looking for the governing equations for the laser radiation on a surface. I understand there are several types and methods. I was wondering if there is an equation to show all the parameters in calculating a surface temperature after laser radiation for a specific time. Some of the...

Does the electric and magnetic fields of electromagnetic radiation remain perpendicular in the presence of an intense gravity field? If not, what is the physical ramifications of this?

would this be a correct understanding of blackckbody radiation phenomena? in particular the intensity versus wavelength curve? "A Blackbody consists of oscillators of molecular dimensions. Intensity is proportional to number of oscillators with sufficient energy hv emitting radiation, and that...

Hello, During the procedure of radiography using x-rays, scatter radiation occurs, due to the difference in densities of the object being radiographed. That scatter radiation causes fogging (noise) of the film, i.e. the contrast of the film is reduced due to extra darkening of some areas of...

Hello, I'd like some clarification with the exact wording of Kirchhoff's law of thermal radiation. The law states that at thermal equilibrium αλ=ελ. However sometimes I read that absorptivity= emissivity and sometimes I read that rate of A. = rate of E. Which one is correct? I'm not sure but I...

A radiation-shielded go-pro camera was sent through an electron beam irradiator. You can see the effects that the radiation has on the camera in the video. I wonder how many rads it was exposed to.

Hello, I've searched a bit about about the thermal radiation behavior of non-black body and I'm confused. I've read that the color is dependent only on the temperature so every thing display the same color as a black body. But at the same time I've read that materials don't always follow the...

Hi every one I have three simple questions: what causes Blackbody radiation? what does Planck meant by the oscillators? why the Blackbody radiation is continuous while the emission spectra of atoms (gases) is discrete? I know that the discrete emission spectra of atoms was explained by Bohr's...

In this paper by Carlip, a comparison is made between electromagnetic and gravitational aberration. For the latter case, he takes as a study subject the Kinnersley’s “photon rocket”, an exact solution which is known to have the strange property of not producing any gravitational waves, even...

In A.P. French's Special relativity the author said, The mass and length of the box are irrelevant here. He said the momentum of the radiation is ##E_{radiation}/c##. We know that the momentum of a single photon with energy ##E_{photon}## is ##p_{photon}=E_{photon}/c##. So is...

Hi I'm a student working on my last assignment in physics department. now I'm trying to make a radioactive radiation detector with the principle of ion chamber. i want to add some new mechanism which when a charged particle pass through the chamber, an LED would emit a light. is there any...

Hello to all, Does radiation pressure depends on the wave phase of the electromagnetic wave hitting a surface? Or, can the radiation pressure be modeled as a sin/cos wave function, where force due to radiation pressure F = P/c would be the average over one cycle? (P = power, c = light speed...

is there a material out there that changes it's properties(for example it's color) when a radiation wave come into contact with it? I need to detect what types of a energies/waves/signals impact a certain object in space (or at least show that radiation hit it some times with great power)...

Inside a CPU, when applying voltage to the gates of the CMOS transistor(high input), are the gate ore another components of a transistor will generate thermal radiation which will be absorbed by the neighboring transistor?

What does a measure of 2000 µW/m² electromagnetic radiation by "Hf35c Rf Analyze (800mhz – 2.5 Ghz)" radiation meter mean? Is it too high? see this link: https://www.electrahealth.com/hf35c-radio-frequency-meter.html it shows that “1000 or more µW/m²” in the meter is “Extreme Concern”, does it...

I am watching this video; at the 8:20 mark it shows that a proton in a magnetic field will align with the magnetic field very easily if there is no shielding from electrons, and therefore will require energy to shift to the opposite spin state; makes sense to me. I also understand that when...

So I was wondering how it is possible that there will be no p-pol light reflected when the refracted light is at 90 degrees to the reflected light (so incoming light is at Brewster's angle). The Brewster's angle was explained to me by saying that the electrons in the medium radiate light...

Hi, i have a question which i can't solve myself, as i am not a student of physics: I have heard of the infinite space curvature which occurs when matter collapses into a black hole. On the other hand i have heard, that a black hole radiates energy away. Now i see a contradiction: When the...

I was looking at Kirchoffs Laws: "A solid, liquid or dense gas produces a continuous spectrum". I would expect objects to produce an emission spectrum since we would be observing the photons that come from spontaneous emission of electrons in excited states. This photons are specific to the...

The radiaton length for air is about $$X_0 = 30420cm$$. This is the length at which the electron has decreased to 1/e of it´ s initially value. I also know that the maximal value of interactions for a specific energy is given by $$ n_{max} = \frac{ln(\frac{E_0}{E_c})}{ln(2)} $$, where E_c is...

I do not know where I am doing wrong. I asked a tutor, he said I was doing it correctly. Below is my work. Please help! Net loss by radiation in 10.0 mins is 74.8 kJ

Radiation pressure that light provides is weak. The photon rocket only gives thrust on par with rockets if you are willing to exhaust way more energy than normally used for rocketry (antimatter/matter annihilation). By that time your exhaust beam will be loaded with enough photons to nuke...