We all know that heat or high voltage makes atoms into an excited state, stripping off the electrons off of their nucleus. But how much heat do you exactly need to create plasma, or have the majority of the atoms to be ionized?
123770
I'm looking for a list of nearly all elements and the temperatures they can reach when in a state of plasma. It is for a project I am working on. However, there isn't a list on google.  Preferably one that is hot enough to survive a drop from orbit.
101522
I am looking for better understanding of how light is produced in an incadescent lamp. More specifically: how is the kinetic energy of electrons converted to light?  Are we dealing with interband transitions or with intraband relaxation involving photons? Is this Bremsstrahlung (electrons lose their energy as light when colliding with crystal impurities/defects)? Or is this a thetmal radiation resulting from Joule heating? How is the emission affected by presence of impurities and imperfections of the crystal lattice? Do phonons play a role? What properties make a material more suitable for use as a filament: should it be a metal? Should it have a crystalline structure? Will any metal produce light, if a high current is passed through it in vacuum?  Update The term describing the processes in the incadescent lamp is , see the posts on this subject  and .
38628
For an object to create different EM waves, it needs to increase the temperature, so what if we or some material could be so hot, that it would emit ultraviolet light, and thanks to that be invisible for the human eye.   I have a lot of questions about this and I would like you to answer me.   At which temperature does an object emit UV light? If an object emits UV light, we wouldn't see anything or we would see some type of violet light? Is there any material that can get to that temperature without melting? Is there any powerful insulator?   Thanks for reading this, and for breaking my dream of making someone invisible, I invite you to day-dream and imagine stupid questions.
7852
This might be a stupid question, but nonetheless, it has been bothering me.  If you take a photon, make it go through some atoms in a solid, liquid or whatever, then you have the chance of this photon being absorbed by an electron, and thereby exciting the electron. This requires the photon to have enough energy to actually excite the electron to another energy level.  My question is then: How does the photon know if it has enough energy or not? Do they interact very quickly to determine if it's okay or not, or is it just something it "knows?"
70100
I know how to calculate the kinetic energy of the emitted electrons   $$KE=hf-\phi$$  And the number of the emitted electrons, but this is valid for a certain frequency  $$N=\frac{IA}{hf}=\frac{P}{hf}$$  What happens if I have a frequency range? for example between λ1 and λ2?  BTW: It's not homework, I'm an engineering student,  not a physics student
21800
When electrons flow through a conductor it is subject to resistive loss, which has the unfortunate capability of producing heat from this current, leaving us with less current in the other end of the conductor opposite to the power source.   When current is lost due to heat, what happens to the electron? I mean, what is left of it? I guess heat is caused by friction, but that doesn't mean that the electron is not able to travel all the way through to the load of the conductor, or what?
90047
This is an extract from the astrophysics chapter in my book:     Hydrogen atoms fuse to form helium.  At the same time, lots of of gamma photons and neutrinos are produced. The photons take thousands of years to "fight" their way to the surface of the Sun, but then escape into space as visible or near visible photons at the speed of light.   I am really confused about how the sun produces light. I understand that through nuclear fusion, energy is formed, but isn't this energy in the form of thermal and gamma photons? I do not understand how visible light is emitted which is the reason to why we see the sun. Could someone please elaborate the paragraph from my book.
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Given that the sun’s temperature is lower than the temperature needed to fuse two protons. How does the sun provide enough energy for this fusion to happen?  Has it do something with tunneling and $E = mc^2$ ? I just can´t seem to understand the concept. If someone could simplify this for me, I would be grateful.   From this , it says " The fusing of two protons which is the first step of the proton-proton cycle created great problems for early theorists because they recognized that the interior temperature of the sun (some 14 million Kelvins) would not provide nearly enough energy to overcome the coulomb barrier of electric repulsion between two protons. With the development of quantum mechanics, it was realized that on this scale the protons must be considered to have wave properties and that there was the possibility of tunneling through the coulomb barrier.".   I was reading through this and my belief was that the sun actually provided a high enough temperature to fuel fusion, however after reading this I am quite confused.
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Liquid electrolytes ionize and hence a current can pass through them. So if a gas can ionize, can it conduct electricity too? If so, what are a few such gases?
21615
I already know the fact that when solid objects heat up, they emit thermal energy which is also known as infrared radiation.  However, if the atoms in that solid were to begin gaining more or less kinetic energy, could the excited electrons then begin emitting radio wave or gamma wave radiation in the far regions of the electromagnetic spectrum?
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I've been told that a vacuum isn't actually empty space, rather that it consists of antiparticle pairs spontaneously materialising then quickly annihilating, which leads me to a few questions.  Firstly, is this true? And secondly, if so, where do these particles come from?... (do the particles even have to come from anywhere?)
22936
So, I was reading Atom: Journey Across The Subatomic Cosmos by Isaac Asimov in order to better understand quantum mechanics when I came across this sentence:      The electron couldn't spiral into the proton because it couldn't take up an orbit with a length less than a single wave.    I was wondering why that is? Why can't an electron not have non-whole number wavelengths in atomic energy levels?
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I don't understand why quantization makes a peak on the blackbody radiation curve (so there is no ) and the relationship between that peak and quantization concept.  When the blackbody is heated, it starts to glow. All atoms start to vibrate. Total heating energy must be divided and equally shared by all atoms of blackbody. Right?  But what happens next?  Do some atoms get much more energy to radiate at higher frequency and waste the energy? What happens at the atomic level, so quantization can explain it? What does classical physics claim, so it can not explain the radiation curve?
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The temperature and pressure everywhere inside the Sun reach the critical point to start nuclear reactions - there is no reason for it to take such a long time to complete the reaction process.  Just like a nuclear bomb will complete all the reaction within $10^{-6}$seconds.  Why does most of the hydrogen of the Sun still not react even though it reaches the critical point, and why take stars billions of years to run out of fuel?
116260
Would it be possible to have a laser that uses atomic nuclear transitions instead of electronic ones?  These are responsible for gamma-decay, so they would produce very high frequency radiation which could potentially be useful.  How would one pump the laser medium?
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Where do the electrons go? In alpha decay do 2 electrons follow the alpha particle and make stable Helium or does the larger daughter nucleus become an anion?  Also what do the electrons do in the mixture of fission and alpha decay? With Beryllium-8 it decays into two alpha particles and 4 lonely electrons or do you get two Helium atoms?If someone could add an entry to Holocron it would be greatly appreciated, thanks.
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Even if the atom is neutral (equal numbers of protons and electrons), the electrons and nucleus form an electrical dipole, so there is still an electric field around them, even though the total charge is zero. Is this reasoning correct? So, every atom has an electric field, even if it is too weak? If not, why?