Questions tagged [electromagnetic-radiation]

Electromagnetic radiation (EM radiation, EMR, or light) is a form of energy released by electromagnetic processes. In physics, all EMR is referred to as light, but colloquially light often refers exclusively to visible light, or collectively to visible, infrared, and ultraviolet light.

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Gamma spectrometry

I want to calculate minimum detectable activity (MDA) at 200 and 300 keV energy of a gamma spectrometry by HPGe detector. 662 keV Photopeak is present for 137Cs. Assume 2 scenarios: There is a 'peak'...
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Does water really have strong EM absorption at 3 kHz in solid and 2 GHz in liquid? Why the huge shift?

While writing this answer to the question Transmitter receiver coil separation for Electromagnetic Terrain Conductivity Measurement I ran across this large PDF file of a book Soil and Environmental ...
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Is there a relationship between loss of electrons and EM wave reflection? [closed]

Is there a relationship between the loss of electrons in a cation and the amount of electromagnetic spectrum, a compound of this cation would subsequently reflect or transmit? For example, any ...
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159 views

What emits the least radiation when hot?

What element with a high vapor point the emits to least light or radiation when heated to its vapor pressure point in a vacuum? Ideally I would like to know in 0 gravity and 0 pressure which ...
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Will gamma radiation cause “thermal” decomposition of sodium bicarbonate?

I am conducting research for a new drug that contains powdered sodium bicarbonate, and the drug will need to be sterilized after placement into it's container/closure system. Typically, this is ...
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De-excitation of a molecule

In our chemistry lecture today on UV/vis-spectroscopy, we discussed the origin of colour in conjugated molecules due to electronic transitions from lower-energy molecular orbitals to higher-energy ...
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What is the relationship between emission and fluorescence?

A molecule exposed to a photon with some energy is put into an excited state, and emits a photon of some energy when it returns to ground state. The photon that provided the energy for excitation ...
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How much heat is created by absorbent-type sunscreens?

I have a friend who claims her dermatologist told her than sunscreen was what was burning her skin. (I think it's much more likely that her rash/burn was either a sunburn, a skin reaction to some ...
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Can visible light or infrared radiation excite electrons?

So the limit of ionizing radiation seems to be UV light. I'm wondering if IR light or Visible light can excite the electrons in an atom. It has to do with the difference in energy level right? So ...
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How much ionising radiation is released during an atomic blast?

I've been looking for how much ionising radiation is produced during an atomic blast (as a percentage). I have seen a claim of 5% of the energy in an atomic blast is ionising energy (Wikipedia), but ...
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Quantization and Bohr's model

According to quantization it's said that emitted or absorbed energy is quantized. Then, when it's said in bohr's model an electron changes its orbit (Let's say it goes to a higher energy shell from $...
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Can gas be made to block radiation better?

Can any gas block radiation? I ask this because I would like to know if the properties of any gas element would chemically react differently with radiation from adding an electrical current. This ...
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Reaction of electromagnetic radiations with the air pollutants [closed]

My friends, who are working on an IoT based technology project, explained their idea to me which is roughly like reducing air pollution by converting pollutants to oxygen ($\ce{O2}$) in any reaction, ...
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Electromagnetic energy to Chemical energy [closed]

How can electromagnetic energy (photons) be efficiently converted to chemical energy? For instance, can water be efficiently split to hydrogen and oxygen using solar energy? As we are running out of ...
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detecting/tracking nano particle [closed]

I am new to nano-sized particles and conducting a very simple experiment using nano particles. In my experiment I have nanomagnetic particles inside water and they are moving due to applied magnetic ...
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How do IR spectrometers produce light spanning the entire infrared spectrum?

An IR spectrum covers thousands of wavenumbers, typically $\sim 4000$ to $\pu{400 cm-1}$. How are the spectrometers able to generate different wavelengths of light covering this entire range of ...
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When precessing nuclei absorb electromagnetic radiations, am I supposed to consider the wave nature or particle nature of light?

I decided to peek into the NMR section of my spectroscopy book, and I found out lots of interesting stuff. And along with the interesting stuff, I did come along some stuff that I didn't understand. ...
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Selective bond breaking

Can a specific bond be broken by an engineered energy wave corresponding to the bond length? For example, can we break the $\ce{C-N}$ bond and not the $\ce{C-H}$ in a hydrocarbon chain?
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Photoelectric effect and kinetic energy

According to my textbook, electrons which are emitted due to the photoelectric effect have kinetic energy given by: $$KE_{electron}=h\nu-h\nu_0$$ Where $\nu_0$ is the activation frequency of the metal....
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What is the quantum mechanical explanation of X-ray diffraction?

One topic in crystallography that I've found a surprising dearth of information on is what the fundamental interaction behind the interaction of the X-ray and atom. Pretty much every book just treats ...
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Why can UV light initiate a reaction between hydrogen and chlorine gas?

Can someone explain me how does UV light help combine chloride gas and hydrogen to produce hydrochloric acid? $$\ce{Cl2(g) + H2(g) -> 2HCl(g)}$$
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How does magentic field change spin values of a proton or electron? [closed]

I am asking this in context of NMR. Firstly I wanna say that I thought that spin values of a proton or electrons were intrinsic. I didn't know that you can change spin states from one value to another....
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Microwaving a glass of water, what happens?

Most of us here would already know the simplified idea behind microwaving food: Microwave radiation hits the water molecules present in food, which excites them and causes 'em to vibrate rapidly in ...
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Formulae for energy of photon (E=hf and E=hv)

I have seen the energy of a photon given by the formulas: $$E = h \cdot f \tag{1}$$ Where $E$ = energy of the photon, $h$ = Planck's constant, $f$ = frequency of radiation (Source: BBC article) I'...
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Are the $+\leftrightarrow+$ and $-\leftrightarrow-$ methanol rotational transitions dipole-allowed?

I am quite confused about the origin and justification of the rotational selection rules of methanol, and I would appreciate any help or references. As far as I understand, there are three irreducible ...
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Grapes in a Microwave - Experiment

I am considering attempting an experiment in which one puts two, almost severed, halves of a grape in a microwave with a glass over it. To my knowledge so far, the grape halves act as focal point for ...
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Stability of Bohr Orbits

In class we had been taught that Rutherford's model was unsuccessful because it failed to show that the orbits are stable because the electrons would lose energy because of electromagnetic radiation. ...
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557 views

How do EM waves cause molecules to rotate, move, and cause electrons to move up energy levels?

Atoms can absorb electromagnetic waves to cause electrons to jump up energy levels, when electrons go down energy levels they release a photon. But how do EM waves cause atoms to rotate, and vibrate?
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Can sunlight and its heat create a caustic or toxic substance from coconut oil on human skin? [closed]

I heard that story quite often, if it's true, how does it work? Notice that I’m not talking about using coconut oil as a sunscreen (it’s another topic) but about the action of the sun on the oil and ...
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Substances that pass visible light but absorb microwaves

Specifically, the substances should be water-miscible or water-soluble, but not water itself. Additionally, they should be absorptive but not opaque.
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What is the reason why protons and electrons do not collide?

can someone give me an intuitive picture of why electrons don't collide with protons? I know that electrons move in a sort of cloud, which is our 'orbital', and that they mainly behave like ...
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387 views

Burning Of Coal and Black Body Radiation

Coal burns with a red glow. What is the ignition temperature of coal? If it is T, and I take another substance which has melting point quite above T, and heat it to T, Will it also emit red light?
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What is generally meant by distinct line spectrum?

In a single hydrogen atom the electron is excited to 6th orbit. The book says maximum 5 distinct spectral lines are possible when the electron comes to the ground state. Looks like they have only ...
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Can gamma radiation cause transmutation?

In irradiation of food for sterilisation, is gamma radiation absorbed by the food? If so, can it theoretically cause production of radioisotopes? Or does it ionise atoms in the food?
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What chemical properties that allow for colour exist in the dark?

Of course if there's no light around, there's no colour that you can see. On the other hand, the wall must have some property that makes it be blue. That property is still there in the dark. — ...
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Transmission, absorption, and reflection of light

My understanding is: when light hits an object, it can do one of three things: transmit through the object, be absorbed into the object, or reflect from the object. However, I have also learned that ...
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Anion formation in an alpha particle-neutral atom interaction?

How can an alpha particle/beta particle/gamma rays interacting with a neutral atom lead to an anion forming? Because i can see how they cause loss of electrons leading to cations forming, but how can ...
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Is there a material that turns from being electrically conductive to non-conductive irreversably upon exposure to some form of radiation?

For my project I am looking for a material which can turn from being electrically conductive to nonconductive (has to be irreversible) upon exposure to electromagnetic radiation (say UV). I tried ...
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Radiating chemical suggestion?

Given a flat and thin object laying on a table, such as a small piece of silver paper or a small piece of cardboard, I want to find a way to detect which face of it is facing up. The solution should ...
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Is Neutron radiation considered electromagnetic wave?

I'm confused because gamma rays are classified as an electromagnetic wave. But why is neutron radiation not considered electromagnetic wave? I know Alpha and Beta, as well as positron and proton, is ...
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Why are certain substances clear/invisible? Can we create invisible objects? [duplicate]

This is more so a question of how light interacts with matter. For example, why are substances like oxygen generally invisible? If the light hitting the molecules were absorbed, it would appear black, ...
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Is there any difference between de-Broglie wavelength and the wavelength of normal waves?

Is de-Broglie wavelength different from wavelength of waves such as electromagnetic waves? If yes, they differ in what respect? And can we use the formula of wavelength of light ($c=v\lambda$) to ...
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Are photons ejected from atomic nuclei?

I have heard that electrons absorb or eject photons when transitioning from one orbital to another. Is this correct? Can atomic nuclei eject photons?
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Why does a mixture of siloxene and cerium(IV) sulfate luminesce?

I performed an experiment where siloxene and cerium(IV) sulphate were mixed together: when I did so the mixture produced an orange-yellow glow. Why does it glow? What is it about the two chemicals in ...
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Wavelengths of the visible spectrum

Why is data about wavelengths of different colors and the visible spectrum in general so different in different sources? On Wikipedia, the numbers differ by up to $\pm\mathrm{30~nm}$.
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Are there non-transparent gases?

Are there gases that are not transparent at room temperature (i.e. at temperature below the point where the substance starts to radiate visible light due to heating)?
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In spectroscopy, is it possible for the sample to be excited multiple times?

The context of my question is rotational spectroscopy (using microwave radiation), where there is the $J = \pm 1$ selection rule. The way I understand spectroscopy is that the sample is irradiated ...
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Can one figure out an optical absorption spectrum from EPR data?

I'm wondering if it's worthwhile for me as an optical spectroscopist to read up a bit on EPR. Do EPR signals reveal where, in terms of wavelength, features in the optical spectrum can be expected to ...
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Is a microwave oven dangerous? [closed]

If we take a look at the electromagnetic specter, microwave wavelength is higher than infrared, which means its energy is very small. To break chemical bonds, the energy required is 100-1000 kJ/mol, ...
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Radiation in space and its effects on chemical reactions?

I know that one current area of research is ways to protect astronauts from ionizing radiation when they venture out of the atmosphere of Earth, but would that same ionizing radiation be a cause of ...