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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What total energy (in kJ) is contained in 1.0 mol of photons, all with a frequency of 2.75 • 10¹⁴ Hz?

There is a question, that says: What total energy (in $\mathrm{kJ}$) is contained in $1.0~\mathrm{mol}$ of photons, all with a frequency of $2.75 \cdot 10^{14}~\mathrm{Hz}$? My answer was: The ...
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Does electron emit photon when it moves? [closed]

When the photoelectric effect happens or blackbody radiation happens or when an electron jumps from a ground to an excited state, we say light is emitted by electron. Now, light is made up of photons. ...
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1answer
138 views

Heat of reaction for the decomposition of AgCl means?

Certain sunglasses have small crystals of $\ce{AgCl}$ incorporated into the lenses, on exposure to light of appropriate wavelength produces a grey colour to reduce the glare following the reaction: $$\...
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About alternative magnetic effect on porcelain (for induction furnace purposes)

I am trying to use the Induction furnace mechanism (like described via this video), for heating part of the Muffle furnace, as one dental porcelain furnace prototype. So, my plan is to put copper coil ...
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Why do molecules showing a pure rotational spectra require a permanent dipole?

I understand that pure rotational spectra only exist for molecules which have a permanent dipole moment. The common explanation is "so that they can interact with the E-field of the incoming ...
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Is it safe to look at a mercury gas discharge tube? [closed]

As part of a chemistry course, I recently observed a demonstration in which the instructor electrified a mercury gas discharge tube (the tube looked something like this image). The glow from the tube ...
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Why does microwave heat up things so much more quickly than visible light?

I wonder why microwave has more "energy" to heat things up than visible light does. Microwave has a much longer wavelength, therefore should supposedly has less energy than visible light. But does ...
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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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How much 'stronger' is water vapor than carbon dioxide, molecule-per-molecule, over the course of a day, in terms of global warming potential?

I have read, many times, that water molecules are far more effective than CO2 molecules at trapping heat... But, the 'relative G.W.P.' value of water vapor (or its 'radiative forcing') is not listed ...
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Raman scattering and "electron and proton center" of molecule

I am currently studying the textbook Infrared and Raman Spectroscopy, 2nd edition, by Peter Larkin. In a section entitled The Raman Scattering Process, the author says the following: Light scattering ...
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absorption spectrum of hydrogen atom [closed]

In absorption spectrum of hydrogen atom, only one electron is present in its one atom which is in ground state, so it means that all electrons can only absorb energy of photon of wavelength which lies ...
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Can reactions produce microwave or radio wave radiation?

I know that many reactions produce visible light, heat and sound, but is there a reaction (preferably one example for an inorganic and organic one) that could produce electromagnetic waves in the ...
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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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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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1answer
79 views

Photoelectric effect with 0 Kinetic Energy?

Does the photoelectric effect take place if the frequency of the photon is exactly equal to the threshold frequency of the metal? I know the electron is going to be free, but it will have 0 kinetic ...
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Radiofrequency transmitter in an NMR experiment: Is there an involvement of (electromagnetic) radio wave?

A student in Chemistry StackExchange asked the effect of radio waves on matter, which led to an interesting set of arguments by some users. It was pointed out that in a proton nuclear magnetic ...
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What are the effects of radio waves on matter?

Different regions of the electromagnetic spectrum interact differently with matter: Microwave radiation can induce molecular rotation. Infrared radiation can induce molecular vibration. Visible and ...
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Do different oxidation states of the same element have the same emission spectrum?

I looked at the flames of copper (I) chloride and of copper (II) chloride through a spectroscope and they looked the same. The flame colour is the same too. But since they have different oxidation ...
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1answer
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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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How do I find mass equivalence of a photon?

The problem has a flame emitting a wavelength of $589\ \mathrm{nm}$, and asks for the mass of one photon of that wavelength. It tells me that $1\ \mathrm J = 1\ \frac{\mathrm{kg\cdot m^2}}{\mathrm s^2}...
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175 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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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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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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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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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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Is the speed of gamma rays equal to the speed of radio waves? [closed]

Does a radio wave or gamma radiation have a faster speed? I know that all light travels at $\pu{3E8 m s-1}$, but does that include these forms of electromagnetic radiation? Or do radio waves travel at ...
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1answer
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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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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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108 views

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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1answer
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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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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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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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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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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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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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1answer
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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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1answer
35 views

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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2answers
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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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Why is beryllium transparent to x-rays?

Beryllium has other fancy applications. It is transparent to x-rays, so it's used in the windows of x-ray tubes, which need to be strong enough to hold a perfect vacuum, yet thin enough to let the ...
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3answers
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Why does the photoelectric effect depend on the frequency of the light?

In experiments to detect the photoelectric effect, a clean metal was irradiated by monochromatic light and electrons were emitted. Why was monochromatic light used in the experiment, and why does the ...
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1answer
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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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1answer
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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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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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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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3answers
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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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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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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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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 ...