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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What is happening over the 15 minutes it takes a neutron to decay?

I've read that free neutrons decay into a proton, electron and neutrino with an average lifespan of about 15 minutes. Is there anything physically different about a neutron that has existed for 14 ...
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0answers
15 views

Is the decay of nuclei also depending on the 'age' of nuclei or whether they are created or not? [duplicate]

Usually the decay is said to be randomly but the average period of decay of certain atoms are stable. So if you randomly take a bunch of the same atoms the average time before the decay will fe be 5 ...
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1answer
80 views

How long will it take to collect enough energy to eject an electron [on hold]

A light source with intensity $1\ \mathrm{Wm^{-2}}$ shines on a piece of potassium. The binding energy of the electrons in potassium is $1.8\ \mathrm{eV}$. The “Bohr radius” of an atom is ...
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1answer
18 views

Dependence of atomic mass number in the Bragg Kleeman rule

I have just staring learning about radioactivity, more or less about alpha particles and how there range can be approximated by the Bragg Kleeman rule, $\displaystyle{R \varpropto ...
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0answers
42 views

Do TV waves pass through solid walls? [closed]

Please give at least one reason. Ty. **My question is: Do television's waves can pass through solid walls? **
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2answers
4k views

Tunneling of alpha particles

Consider this explanation of the alpha decay: It says The Coulomb barrier faced by an alpha particle with this energy is about 26 MeV, so by classical physics it cannot escape at all. ...
12
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1answer
229 views

In the Iranian nuclear deal, how can IAEA detect nuclear activity after 24 days?

This is a question related to current events, but I want to ask about the physics, which are not explained in any news article that I can find. Ernest Moniz and John Kerry wrote an op-ed in the ...
10
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3answers
838 views

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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0answers
21 views

Purcell's approach to Larmor's formula, assumption?

In 'Electricity and Magnetism' By E.M.Purcell, a derivation is given of Larmor formula (a version of which can be found here). I will give a brief overview here: A particle is considered at ...
3
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2answers
117 views

Where are the photons coming from?

Particles and Antiparticles can annihilate, and they are completely destroyed in the process, which creates photons. From wikipedia: ...
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1answer
54 views

Inverse beta decay; energy of anti-neutrino

Assuming that the target protons are at rest, calculate the minimum energy of the anti-neutrino for this reaction to take place: $$\bar{\nu}_e+p\rightarrow e^++n$$ I know the answer is given by ...
11
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2answers
1k views

What temperature can you attain with a solar furnace?

A solar furnace is a device that concentrates the sun's light on a small point to heat it up to high temperature. One can imagine that in the limit of being completely surrounded by mirrors, your ...
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3answers
2k views

Does brightness of the light remains constant with the variation of the distance with respect to the source in vaccum?

I have this question going in my mind from many days, i.e why brightness of light emitted from any light source around us decreases with distance? The brightness of light from tube light, streetlight, ...
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1answer
20 views

Radiation-Glossy Black vs Matte White

Well, studying the chapter Heat I know that a matte black body radiates heat more than a glossy white one but can anyone give me an answer about what happens when its a glossy black body and a dull ...
1
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1answer
53 views

Would 10 metres of liquid air be as effective against cosmic radiation as Earth's atmosphere? [closed]

Assuming ballpark figures which give a depth of 10m if the Earth's atmosphere was liquefied, would that be as effective a protection against ionizing radiation from space as the gaseous atmosphere is? ...
0
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2answers
60 views

What is beyond Gamma Rays and Radiowaves in the Electromagnetic Spectrum?

The electromagnetic spectrum is commonly refered to as consisting of; Radio-waves, Microwaves, Infrared, Visible Light, Ultraviolet, X-rays, Gamma Rays - of increasing frequency from left to right. ...
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1answer
44 views

Do all solid objects emit visible light?

Are there solid objects that do not emit visible light? To my limited and humble knowledge, creating such an object would require us to "only" shift the spectrum of emitted radiation. Is it possible? ...
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4answers
3k views

Decay of massless particles

We don't normally consider the possibility that massless particles could undergo radioactive decay. There are elementary arguments that make it sound implausible. (A bunch of the following is ...
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0answers
13 views

Difference between PIN photodiode and silicon surface barrier in beta spectography

In a physics undergraduate lab we performed an experiment in spectography of beta decay. We used two detectors to measure the energy spectrum of Bi207: PIN photodiode Silicon surface barrier ...
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0answers
35 views

Why build so big sarcophagus in Chernobyl instead another alternative? [closed]

As title, why build so big sarcophagus in Chernobyl? The new sarcophagus is really tall, large and expensive and it should cover the old one. But there is already a sarcophagus build over another ...
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0answers
26 views

Bremsstrahlung in body tissue

As far as I know, the intensity of the produced radiation from bremsstrahlung is proportional to: $$I \propto \frac{Z^2}{m^2},$$ where $Z$ is the atomic number, and $m$ is the mass of the particle. ...
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2answers
32 views

Diminishing solar temperature and its effects on earth

This is a hypothetical question; considering both the earth and the sun as black bodies. If the temperature of the sun decreased N times, what would be the effect on the radiation intensity received ...
0
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0answers
19 views

Do alpha particles add to the mass of the matter they are interacting with?

If a large number of alpha particles are fired into a target material, they presumably interact with the matter by ionisation and eventually lose energy, and are 'absorbed' by the target. Do they ...
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0answers
36 views

Does elementary particle decay simply swap mass for speed?

I'm looking at different decays of elementary particles. And I am wondering about the masses (in energy) not matching up. For example, W and Z bosons are far more massive than the particles that decay ...
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1answer
51 views

How to shield myself from the LTE radiation coming from my phone while working on my Laptop? [closed]

I am connecting to the internet with the tethering option on my phone. I wonder if there is a way to shield myself from the LTE radiation (Long-Term Evolution, commonly marketed as 4G) as I am exposed ...
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2answers
34 views

How to combine albedos

I have estimations of the Earth's surface albedo for a region (0.13), as well as an estimation of the atmosphere albedo (0.3 at a solar zenith angle of 1 rad). My question is, how do I find the ...
3
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1answer
42 views

How much ionizing (carcinogenic) radiation is one exposed to on a commercial flight, what are the sources, and how could exposure be minimized? [closed]

I don't know if this is the best place to ask this question, but I figure a physics-based answer would be the most satisfying. I'd be happy to be convinced I'm being paranoid about protecting an ...
0
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0answers
57 views

Cherenkov Luminescence Imaging, Cherenkov radiation,

Is it possible to see glowing from Thin Layer chromatography (TLC silica gel on Aluminium) when we image it by IVIS spectrum (no radioactive source)?
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4answers
64k views

What exactly is the difference between radiation, conduction, and convection?

Okay, so everywhere I've read, I hear the main difference is the requirement of a medium. But for example, if you take the case of heat 'radiating' from a red-hot iron, isn't that actually convection ...
3
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1answer
28 views

Confusion about the shock growth

I am studying Hamilton's & Blackstock's Nonlinear Acoustics. One of the essential phenomena associated with a finite-amplitude (unidimensional, planar) sound propagation is building the shock due ...
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1answer
19 views

Why is beta-minus decay considered isobaric?

Page 20 of Physics in Nuclear Medicine says that beta-minus decay is isobaric (eg the A/Z ratio remains the same). The reason it gives is that "mass number A does not change." However, in beta-minus ...
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3answers
23 views

ionizing radiation and energy

At the website "How Stuff Works" an article (radiation sickness) states that when radiation knocks an electron from an atom, energy (specifically 33 electron volts) is released which heats up the ...
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0answers
11 views

Temperature equalization by radiation between two coaxial cylinders - independent of diameters?

Ignoring end effects, assume I have a cylinder of diameter d0 at controlled temperature k0 and then introduce a smaller diameter cylinder of diameter d1 and temperature k1 to the interior. Does the ...
0
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1answer
23 views

Conceptual Doubt regarding the calculation of the Solar Constant

The Solar constant is the intensity of the solar radiation in the upper atmosphere. It's value is about $1400$ $Wm^{-2}$. Now we begin by stating that the Power radiated by the sun is about ...
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1answer
34 views

Why beta+- decay occurs?

So nice place to ask question like this here. I have read some basic physics magazine like Newton monthly. There I saw article about nuclei generation in star. I want to know more and found wiki ...
0
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0answers
13 views

Proton Spread Out Bragg Peak vs. lateral beam broadening (Radiotherapy)

I was wondering. When particles enter a medium it has a finite range until it reaches the Bragg Peak where it deposits most of its energy. Now, heavier ions means less lateral broadening of the beam ...
0
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0answers
7 views

Why do Photochromatic lenses react to temperature changes?

So, I'm aware that Photochromatic lenses are affected differently due to different ambient temperatures. From what I've read it seems that the molecules rearrange their structures slowly in cold ...
0
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0answers
32 views

Does gamma radiation create radioactive people?

I've read that the materials become radioactive. I'm writing a story where an unfortunate person has been in the vicinity of a large amount of gamma radiation. They've absorbed 6-8 Gray. Would the ...
0
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0answers
21 views

How much energy would be required to remotely induce a signal in a wired network (e.g. Ethernet)?

How much energy would be required to remotely induce a signal in a wired network, such as Ethernet? Assume, for the sake of discussion, that the wired network has a single cable of length $l$ (eg 10 ...
0
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1answer
24 views

can superconductors and other meisner materials be used as magnetic shielding in space to protect diamagnetic artificial gravity of 45 teslas?

I have seen people referring to Geim's floating frog that a human in 45 Tesla's would be held to the ground from diamagnetism above them. A very real but crude artificial gravity using powerful ...
3
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1answer
3k views

Finding electric power generated using heat transfer

I'm working through an example I have been given to study. Suppose I have a 2m X 4m photovoltaic panel on my roof that is irradiated with a solar flux of $G_s = 700W/m^2$. Given: $\alpha_s = 0.83$ ...
0
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0answers
26 views

How to see alpha radiation

Hello I am looking to replicate the double-slit experiment using alpha radiation from a sample of Polonium-210. Keep in mind that I would need to put it in a vacuum so cloud chambers would not work. I ...
0
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0answers
15 views

Finding the geometric efficiency of a cylindrical Marinelli beaker

I want to find the geometric efficiency of a cylindrical marinelli beaker filled with soil to perform gamma spectroscopy, so essentially the ratio of rays that pass through the detector to the overall ...
0
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2answers
293 views

What is the amplitude of the electric field in a laser?

I'm looking for reliable informations about the amplitude (not the intensity), in volt/meter, of the electric field in a typical laser. Or in other words : what are the typical amplitudes of the ...
3
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1answer
32 views

DNA breaks with particles or photons (Radiation therapy)

When protons (or other particles) or photons are used in radiation therapy to treat cancer patients, the main effect is for it to make DNA breaks that hopefully will make the cancer cell die ...
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2answers
32 views

Black Body radiation (intensity in certain distance)

i need some help with this task: I have a black body radiator which is spherical and it has radius $r=0.56m$. It radiates with intensity $1.5\frac{kW}{m^2}$. I would like to know the intensity in ...
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2answers
39 views

Emissivity and Final Temperature of a Black and White object

Objects can be categorized as blackbodies (emissivity $\epsilon = 1$), grey bodies (emissivity $\epsilon < 1$) and white bodies (emissivity $\epsilon = 0$). If we placed two objects (identical ...
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0answers
46 views

Carnot Engine- Cold Reservoir is a black body [closed]

My question: A satellite powered by a Carnot engine uses heat from a nuclear reactor at a fixed temperature T0. Heat is released into outer space via thermal radiation emitted by a set of fins at ...
7
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4answers
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What common materials absorb most infrared light?

I'm competing in a simple robotics competition where most of the participants use reflected infrared light to detect their opponent. I'd like to make my own robot as difficult to see as possible. What ...
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1answer
55 views

In a waveguide, where does the energy in attenuated waves go?

In an electromagnetic waveguide, there is generally a "cutoff frequency." Electromagnetic waves with a frequency that is lower than this cutoff frequency will not propagate at all -- i.e., they will ...