Radiation Definition and 1000 Threads

I am curious about the historic experimental evidence that lead to Kirchhoff's radiation law. It is easy to take for granted the ubiquitous temperature/wavelength curve that lead Planck to the quantization concept. But I wondered historically how the curve was derived. To clarify, we...

Homework Statement: More of a conceptual question than a homework question. Maximizing radiation southward and minimizing it northward. Homework Equations: (See picture in attempt at solution) For two antennas separated along the north-south direction, operating with the same amplitude...

I thought the answer was C because what's not to say when surface is placed 6 cm from radiation detector beta particles are also present, and that surely all beta particles would be stopped with a 1cm thick aluminium plate?

I tried modeling the problem quite a few ways. one was to say that the difference between the heat emitted by the room and the heat emitted by the bulbs would equal the heat absorbed by the room, and that could allow us to calculate temperature. This did not work. I'd appreciate your help

[Moderator's note: New thread spun off from previous discussion due to more advanced subject matter being discussed.] There is, in fact, a quite good argument that Hawking radiation cannot be derived by semiclassical theory. It is the comparison with the scenario where the collapse stops some...

Hello! In the descriptions of the BB radiation that I read, I see that we assume we have a cavity at a fixed temperature in equilibrium, we make a hole in it and we look at the intensity of different frequencies emitted through that hole. As far as I understand, the intensity dependence on the...

Hi, I am looking for the best way to either shield or redirect radiation, particularly Gamma radiation away from vehicles in space with the minimal amount mass. The last thing we need is a few feet of lead. I am hoping to find other options. I would love to redirect radiation away from a...

Hi all, My first post on this forum. I couldn’t think of anywhere better to come than to here with a question I’ve had since a recent trip to Chernobyl! Whilst visiting Pripyat I took several videos. Great care was taken to stay away from any contamination hot spots and we had an experienced...

Interesting article ...NEW SOURCE OF SPACE RADIATION: Astronauts are surrounded by danger: hard vacuum, solar flares, cosmic rays. Researchers from UCLA have just added a new item to the list. Earth itself.“A natural particle accelerator only 40,000 miles above Earth’s surface is producing...

https://www.abc.net.au/news/2019-08-09/russian-rocket-explosion-kills-two-sparks-radiation-concerns/11398604 Radiation has been released following a Russian rocket explosion at the Nyonoksa naval ballistic missile test site. Part of the White Sea has been closed. 5 people now reported killed...

I'm trying to get a better understanding of CBR. Unfortunately the internet has limited information, I guess it's not a cool enough of a topic to discuss. This is some of what I found, is it correct? CBR is electromagnetic radiation. Microwaves travel at the speed of light. CBR was a result of...

We want to calculate the ao/a(teq) of the equilibrium point between ρm and ρr (ρm= ρr ) My book solves it this way; ρm(t) / ρr(t)= a(t) ⇒ ⇒ (ρm/ ρr)teq =1 = = (ρm/ ρr)o * a(teq)/ ao I don't understand the a(teq)/ ao part. If ρm(t)= ρο/αo3 and ρr(t)= ρο/αo4 then it should be ρm(t)/ ρr(t) =...

Trying to understand the concept of heat. As I understand it, heat is really just kinetic energy. In Newtonian mechanics, it is 1/2mv^2. Here are my questions... (1) On a microscopic level, are conduction and convection simply atoms bumping into each other and passing along some of their...

If a double slit experiment utilized photons from Cherenkov radiation under water, Would we expect the same results?

It is known theoretical prediction that Black Holes must emit radiation "... its temperature and surface gravity are proportional to its mass divided by its area" (Kip Thorne). This is applied to Event Horizon (rg). But one can imagine inner Black Hole (e.g. inside r' < rg), it does not have...

Hi everyone! I'm new to this forum, so I hope my question fits into this category. Yesterday I wanted to check if I could measure any radiation from Radon in my basement with my Radiascan-701 Geiger counter which features a pancake-style probe that should be able to handle alpha, beta and...

Does direct radiation increase as the zenith increases? I know the diffuse radiation increases as zenith does, but is it the same for direct Also is it right to say that when diffuse radiation increase, the direct should decrease and vice versa? edit: My book says diffuse increases as we...

What is the relationship between spectral coherence with respect to a radiation source's mean wavelength and bandwidth? I have no idea how to estimate, given a particular radiation spectrum from a source, what it's spectral coherence is going to be.

is there some physical limit on the wavelength of electromagnetic radiation? Can there be radiation shorter than gamma rays?

Why do high levels of radiation taste like metal?

Summary: As hawking radiation is based on quantum fluctuations, can they cancel out each other due to equal probabilities of a particle remaining in or drifting away? I recently learned how hawking radiation actually works. It is based on quantum fluctuations which happen randomly in space...

During episode 2 of the HBO miniseries “Chernobyl”, the search lights held by the three technicians entering the area beneath the reactor eventually go out from exposure to radiation. If the search lights were powered by lead acid batteries, how does radiation interfere with and/or hasten the...

I'm confused on how something can absorb visible light and release heat. Specifically, I'm confused how the Earth absorbs visible light and emits IR + heat. I'm in a class (about global warming) for non-science majors and don't have much of a background in science, so I would appreciate...

Recently I am learning about electrodynamic radiation and its various types, and it occur to me that since the form of the magnetic field created by the dipole radiation is some combination of cos(wt), 1/r, and cos(kr) (take the approximation of r >> c/w) Therefore, if there is a metal placed...

Glasshouses warm because supposedly heat (infrared) is trapped inside. However I am looking for a description of the process. Is it by glass reflecting infrared back into the glasshouse, or is it by glass absorbing infrared, heating up itself and then warming the glass house interior by...

Trying to understand radiation near black holes, specifically sgr-a, and more generally "radiation in space" and its general threat to the survival of spaceship occupants. Please let me know if this would be more appropriate in a different section here, eg astrophysics. In my little story the...

I don't know where to even begin?

I have solar radiation data in the units of Joule per cm^2 (joule per square centimeter) measured hourly. I want to use this data in evapotranspiratin calculation which requires radiation units as Watt per meter squared. How can I do this conversion?

I know that has been discussed elsewhere but never could find for a satisfying answer, so I try this here again. Let us not take into account that an observer (an astronaut or a clock or just let us take both: an astronaut with a clock) falling into a black hole (BH) will be killed and torn...

I am quite confused, as I start this question. I can easily find the following when searching up Planck's law: However, this is not u. My prof is quite unclear and sometimes chooses his own variables as he sees fit, so i am not sure if this would be equivalent to what he is looking for u(λ)dλ...

Hi everyone I have some trouble understanding quantum physics. Here is a scan from the book from Eisberg and Resnick Here is how much I understand. This is radiation inside cubical cavity, λx/2 is distance from two nodes of component x of the radiation. Same goes for y and z components. In the...

Homework Statement A dose of 5 Gy of X-rays is required to destroy 63% of a particular bacterial population. It requires 1 Gy of beta particles of mean energy 1.0 MeV to accomplish the same result. What is the wR for the beta particles in this population of bacteria? Homework Equations H= (wR)...

Hi, I wonder why with electromagnetic radiation, there's some radiation that penetrates with Earth atmosphere such as visible light, while other can't like gamma radiation. What does the penetration of any em radiation on any object depends on

How ,exactly, are gamma and beta radiations produced in electron accelerators? Is the process for gamma almost the same as X-ray in linear accelerators? What about beta?

Recently, the origin of the cosmic microwave background as a relic radiation of the Big Bang was questioned and an idea of the CMB as thermal radiation of cosmic dust was revived and revisited. Under this theory, the temperature of the cosmic dust is predicted to be 2.776 K which differs from...

Hello: Do anyone remember a law to calculate an area of a sphere ,some thing like the specific surface area but relative to absorption of radiation ?

Hi, In the Stefan-Boltzmann equation for radiation heat transfer, there exists expected parameters of any model (area, constants, etc.). However, the temperature is raised to the fourth power. Can someone explain why? I get that it could just be because it has been "experimentally observed."...

So, I have no education in this field. I've really been into mutant breeding and crisper plasmid based genetic engineering. I've read that heavy ions create a greater number of mutagens than electron magnetic radiation such as deep uvc. lately particle accelerators have been on my mind. I'm...

This may be a ridiculous question but I wanted to find out whether it would be possible to heat a 10x10x5 mm sheet of inconel 718 alloy (weighs around 500 g) to 1000 degrees C using a bunsen burner. The burner I have in mind is the Integra Fireboy safety bunsen burner (link below). It has a max...

So I see EM radiation , visible spectrum including being portrayed as two sinewave vectors each perpendicular to other one being that of the E field the other being the B field, the field is carried by photons, let's take the visible spectrum as an example. So having a specific frequency the...

I'm having trouble verifying an experiment I ran to determine the power dissipation of a heating element. 13.15W of power was applied to 3ft nichrome wire. Temperature readings were collected until they stabilized at 128.5F (room temp was 70F). I want to create a mathematical model of the system...

Good evening, As part of my course, I had this week two lectures about the blackbody radiation and its relation to the stars. While I do understand how to use results such as the Stefan-Boltzmann law and Wien's Law I'm lost in other parts. I think the only parts that I don't understand yet are...

I have two questions (1) If we have two areas, for example one in America and the other on Asia, both with the same latitude φ, which one of the areas will receive more Solar Radiation? Or will it be the same? (2) If Earth's eccentricity graph for the past 750k years is this...

How does radiation from a star clear dust from a proto-planetary disc, changing the area from one of opaqueness to one of transparency? Please note that I am a retired engineer with an interest in astronomy, cosmology and particle physics but very much a layman..

Stephen Hawking theorized the creation of virtual particle pairs at the event horizon of a black hole, with one of the particles escaping the event horizon (Hawking Radiation) and the other particle falling into the black hole. Sean Carroll states on page 272 of From Eternity to Here that "if...

Hi All, Can somebody tell me what's the speed of the Graviton? As for Cherenkov Radiation, does exist a similar effect for Graviton? Thanks

If I have a beam of protons that go into a block of water, how can I know how many photons will be produced along the beam path?. I'm assuming all the photons have the same energy. I know that the energy deposition will follow a Bragg Curve, and I think that energy deposition is probably...

Hawking Radiation says that an antiparticle and particle spontaneously appear and annihilate each other everywhere, but at the horizon, if the antiparticle appearing inside the horizon and the particle appears outside, then the antiparticle is sucked in and the particle is emitted outward...