Radiation Definition and 1000 Threads

we say everytime a couple of matter-antimatter particles get born near the edge of a black hole one of them falls into it and the other one escapes. And we everytime mention that the antimatter particle kind of eats a bit of black holes mass out...and by time the black hole gets smaller and...

Homework Statement One end of a solid cylindrical copper rod 0.200 m long and 0.0250 m in radius is inserted into a large block of solid hydrogen at its melting temperature, 13.84 K. The other end is blackened and exposed to thermal radiation from surrounding walls at 500.0 K. (Some telescopes...

If you heat something by radiation, its temperature increases, which means there is an increase of the average velocity of the atoms the "something" is made of. Another thing which happens when radiation hit the object, is that its atoms can "absorb" photons, as electrons go to higher energy...

What is the difference between the photon interaction mechanisms in emission due to absorption and reflection?

If there was background radiation of say 1.95K what would be the correct way to calculate the temperature of radiation at t1? Do we need to know what t1 is and also i have looked at Stefan Boltzmann law but i do not think that formula would be appropriate for what is trying to be achieved here.

I just want to know the formula for the following question: If the dose rate from a sample of Ra-223 was found to be 20 mSv per hour at 10 micrometres, calculate the dose rate at 30 micrometres. Show your calculations. Give your answer to one decimal place. I think it is 20 mSv x 10 micrometres...

What is the best analogy to explain electromagnetic fields? I have seen the depictions of em radiation as perpendicular waves. Do we exist in a huge sphere of em radiation in which waves such as cell phone signals and radio broadcasts can be thought of as spherical ripples that emanate at the...

Hi All I read somewhere that at close to C the light emitting from a regular light globe ie diffuse light in all directions, will form a cone. what is the thinking behind this and does anyone have a link where I can read about it ?

Homework Statement 1.) A piece of bread (ε = 0.85) is being toasted in a toaster, as shown below. The heating element of the toaster consists of a wire 2 mm in diameter that is wound to approximate cylinders spaced 2 cm apart. This element acts as a blackbody. The housing for the toaster is...

So in chem lab we were doing experiments in radiation and the TA seems to have no idea how to do stuff, he told us to hold the samples at certain distances from a Geiger counter for 2 minutes at a time. I was tasked with holding an Sr90 sample for roughly 25 minutes, it was a very small sample...

Homework Statement The problem is state in the attachment. Homework Equations None to add. 3. The Attempt at a Solution Struggling with this problem because of the phasor part of it. Perhaps this is justified because the angle is very small and so that relates to a low frequency? Is it...

Hello everyone, "Does a charged particle radiate in free-fall?". I read many threads on this subject and I was surprised to find out that there is no unanimous "Yes or No" answer to this question. Here is an interesting answer from researchgate.net: The question is widely discussed in the...

I'm talking hotter than T = 6000k. The higher the temperature, the more the curve in the attached figure would shift to the left (while at the same time getting higher). So the intensity peak would eventually fall back into the invisible portion (very small wavelength this time) of the...

I am interested to know if cosmic microwave (160 Ghz) or cosmic radio (20-50 Mhz) background radiation has ever been measured/detected underground or underwater? This may seem like an odd question as you’d expect lots of rock and water to attenuate or block the cosmic radiation photons, but I...

3D Subsurface Laser Engraving works for clear glasses like Schott BK7 and B9 Borosilicate Glass. How does one do the same for relatively translucent minerals? I have read research papers on using lasers for tattoo removal and cancer radiation therapy. However, I want to know how the laser's...

Hi. I want to know does thermal radiation contain all the wavelengths (from very near zero to almost infinity) or not? I want the thermal radiation of normal things like hot Tungsten (wolfram) or hot Iron. I don't want the black body radiation of a star. I think, theoretically it must contain...

The field of quantum mechanics was launched with scientists struggling to understand blackbody radiation. My question is: what is the source of this observed radiation? Is it the nuclei in the matrix of the metal jiggling around ever more energetically as you heat up the metal? Or is it the...

I have been considering Hawkin radiation and I am puzzled about the capture of a virtual photon. Given that the escaped photon is entangled with the captured photon I do not see how the escaped photon can shed the entanglement. Can anyone help with this?

Please, moderator, just delete this question if it is too silly. I am wondering what is happening in anyone point in the SpaceTime field. That's what it is called, I think? Because my simple understanding is that we see colours/light because of propagated electromagnetic radiation at...

Homework Statement [/B]Homework EquationsThe Attempt at a Solution I find something contradictory about the cherenkov angle for the above two image[/B]

The Feynman LECTURES ON PHYSICS (NEW MILLENNIUM EDITION) by FEYNMAN•LEIGHTON•SANDS VOLUME II discusses radiation from an infinite sheet of switched-on constant current in section "18-4 A traveling field" on page 18-15. The solution shows a constant E field and constant B field at a given point...

Hi guys, I'm wanting to test materials developed in CAD software for their radiation blocking qualities (EM Spectrum), I would ideally need to use a software where I can set the wavelength and frequency of the emitter and set up a receiver, allowing me to place different materials in the middle...

Could anyone recommend a textbook or a pdf available free online, which has exercises with solutions in Radiation Dosimetry? Thanks in advance

Why does a tungsten filament light bulb (or any heated metal for that matter) emit EM radiation (both visible and infrared) - is the EM radiation due to vibration of molecules or electron excitation?

Suppose I were to subject a polar molecule to a high-frequency electric field. The polar molecule responds to the high-frequency electric field and thus it has a time-varying electric dipole moment vector. If we treated this as a classical electric dipole, it would be expected to radiate some of...

Hi everyone. I was thinking about the question that I stated in the title. If you are exposed to radiation, such as alpha and beta particles, you don't emit radiation. The alpha particles are merely stopped because they don't have a high penetration. The beta particles pass through your body and...

Hi, I've been trying to de-misinform myself about the Chernobyl disaster in relation to radiation exposure. I found this study on the WHO website that states, Main points I would like to bring up: Source. Now, it seems that the source of my confusion is due to some apparent shortcomings...

I cannot understand the expression "air does not intervene with radiation". Would you please explain what it means in detail? " Considering that air does not intervene with radiation and the person is completely enclosed by the surrounding surfaces, the net rate of radiation heat transfer from...

Hi everyone, I am currently working on a project in Physics analyzing the possibility of magnetic fields protecting against radiation particles such as fully ionized nuclei or electrons. I wrote a code in Matlab that simulates a 3-D magnetic field based on a combination of wires and wire loops...

Hi all, I'm performing a thermal analysis of a satellite subsystem (antenna). However, I'm having some issues relating to the model that I'm implementing on ANSYS. I've already computed the values for the solar flux, albedo and IR that the satellite is subject and I've applied it to different...

So I have an old RCA Thyatron tube (model 3C23) I'm using in an art piece as a glowing element. Just feeding maybe 50-60 watts through the anode to make it glow. My question is, do I have to be worried about UV radiation? I heard somewhere the glass was quartz or borosilicate and blocked it...

When a charge is accelerated it brakes because it emits radiation. If a carge is accelerated with costant acceleration and the traiectory is a line what is the frequency of the emitted radiation? (I think 0Hz but i am not sure)

Hi everyone. I read from: https://www.nucleonica.com/Applet/NaturalRA/Button5/page5.html that inside the human body, 4400 of K40 atoms disintegrate every second through radioactive decay. Of this decay, 11% (480) results in gamma radiation, and 50% of that 11% (240) escapes the body. My...

Homework Statement Question attached. I want to check what values of WT I should use. Homework Equations Effective dose = WT*WR*WT,R The Attempt at a Solution For the neutron whole-body dose I have WT = 1. For the ingested 90Sr and 131I, I also have WT = 1. Are these correct or does...

Consider an excited hydrogen atom in state n moving with a velocity v<c. it emits a photon in the direction of its motion and changes its state to a lower state m. Find the frequency of emitted radiation in terms of frequency fo if the atom were at rest. My approach: I tried by taking recoil...

Hi, I’m currently at college for my B.S. in physics and I’m working toward my minor in bio. My original goal was to go for a B.S. in physics and then through the program offered by my school, get a M.S. in engineering. However, I had a change in heart beginning of last semester and dropped the...

Ive been reading about it for a while and I'm still confused. i understand that a star is not a perfect blackbody. but do stars absorb radiation from space and then re-emit that energy into space?

Matter with negative mass, herein called “negative matter”, is different from antimatter. P.A.M. Dirac, on theoretical grounds, proposed the existence of antimatter, and its existence was later confirmed by experiment. Antimatter is the opposite of ordinary matter in some ways, but just as...

Homework Statement Homework EquationsThe Attempt at a SolutionThe energy density is given as ## u = \frac { 8 \pi {\nu }^2}{c^3}~ \frac { h \nu} {e^{ \frac { h\nu}{k_B T}} – 1}.## EDIT : I put the constant C. ## \frac { u( 2 \nu) } {u(\nu)} = C \frac { {e^{ \frac { h\nu}{k_B T}} – 1}...

Homework Statement I have attached a picture of the question. A 2 Ci 137Cs source is equal to 2 x (3.7x1010 Bq) = 7.4x1010 s-1 8 hours a day, 5 days a week and for 50 weeks is a total duration in seconds of 7.2x106 s An 8 cm lead shield = 0.08 m IRR99 regulations set an effective dose...

Point Particle in Relativity and Electrodynamics: “The Classical Theory of Fields” – by Landau and Lifshitz, in its discussion about classical size of a particle, concludes that:- Thus we come to the conclusion that in classical (non-quantum) ‘relativistic mechanics’, we cannot ascribe finite...

What exactly is the physical origin behind light produced by Cherenkov radiation having a non-zero angle with the trajectory of superluminal charged particle? Why is the light simply not allowed to go in any direction? Also, is Cherenkov radiation observed for "uncharged" particles (e.g...

When I study any book of Quantum Mechanics like Resnick or Beiser etc all start with blackbody radiation! But how this radiation is produced? Google says due to increased collision of particles causing the acceleration and em wave but what particles? How they are accelerated from what? Like if...

Homework Statement Homework EquationsThe Attempt at a Solution From the equation it is clear that the wave is propagating in y direction. So, the magnetic field is along z- axis. ……….(1) Dimensionally B = E/v……….(2) According to the above two conditions , the correct option is (c). Is this...

Homework Statement Homework EquationsThe Attempt at a Solution E = (13.6 – 3.4 = 10.2)eV = ## \frac {hc } { \lambda } ## =1.22 * 10^{-5} cm So, the correct option is (a). Is this correct?

Dear all, I'm trying to understand the firewall controversy and the role of Hawking radiation in this. To make things concrete, I'll use the desciption of the firewall controversy of John Preskill here...

A non ionized neutral gas should still emit thermal radiation.,say xenon. Is this solely because of electron transitions ? I ask this because a lot of sources attribute the emission to charge particle acceleration,so neutral atoms should not do this,is this right?

Hello, I am a Mechanical Engineering student but I am a TA for an electricity and magnetism course, and I had a student ask a question that's a little bit outside my understanding. The question was related to the equation for a radiating electric field from an accelerating charged particle...

For the proof I've read that verifies transverse electromagnetic waves are consistent with Gauss' Law, there seems to be the suggestion that the magnetic and electric field at a given small length c(dt), along which the waves travel, propagate infinitely backwards and forwards in their...

In this page https://en.wikipedia.org/wiki/Matrix_mechanics I don't understand this statement : "When a classical particle is weakly coupled to a https://en.wikipedia.org/w/index.php?title=Radiation_field&action=edit&redlink=1, so that the radiative damping can be neglected, it will emit...