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1h
comment What is the difference between Raman scattering and fluorescence?
@JohnRennie well ,I see, the famous field theoretical framework. Us experimentalist when we see an electron hitting a proton and losing some energy on the proton call it the same electron.
2h
comment What is the difference between Raman scattering and fluorescence?
@JohnRennie just saw this. Of course a photon can interact and not be absorbed, "compton scattering" and "elastic scattering in cms" , just get lower frequency, the equivalent can happen with a molecule and a lattice too.
2h
comment Is there a preferred mode of exchange of gluons?
It is not simple. do read en.wikipedia.org/wiki/Gluon#Numerology_of_gluons
6h
comment Thomson scattering cross section: free electrons vs atoms
The atom is neutral, so taking the charge of the atom means zero to zeroth order. The electron interacts with a virtual photon with the spill out fields of the speficic atom, due to the complicated shapes of the orbitals. You need atomic form factors to get at crossections nist.gov/data/PDFfiles/jpcrd67.pdf
7h
comment Why is there no current flow when i connect two opposite terminals of two separate batteries
@justin I cannot teach chemistry. The way the chemical reaction works has been utilized in the set up of the battery. There is no if about the way the energetics of chemical reactions go.
7h
awarded  Enlightened
8h
awarded  Nice Answer
9h
comment Why is electrical energy so difficult to store?
@justin The water deposited on high lakes etc, comes from rain, and rain is powered by the sun ( evaporation) . One can increase the mountain water by using solar panel electricity to pump from a low reservoir to a high one, a gravitational storage
9h
comment Why is there no current flow when i connect two opposite terminals of two separate batteries
@justin if the copper is not deposited the SO4 will not carry a charge(-2), read the diagram, it shows how ball is played with the charges and the copper and zink . There can be other electrolytes, but not randomly guessed. The chemistry has to work. .
14h
comment Why can't incoherent light be collimated as well as laser light (e.g. in a laser pointer)?
@Ruslan yes, but we are talking of a pencil pointer here, and whether it makes sense to use a LED or a laser. I have to go now so I will look at this after doing my chores.
14h
comment Why can't incoherent light be collimated as well as laser light (e.g. in a laser pointer)?
@Ruslan are you saying that ,lets say, a 1mwatt laser pointer and a 1mwatt LED can deliver the same power to the spot on the screen?
14h
comment Why can't incoherent light be collimated as well as laser light (e.g. in a laser pointer)?
@Ruslan and the fact that the power of the laser is concentrated in a parallel beam versus the LED which is 4pi plays no role in making the LED useless for a pointer?
15h
comment Why can't incoherent light be collimated as well as laser light (e.g. in a laser pointer)?
@Ruslan I think it is small because it is constructed to be small , it will be a pointer after all. madehow.com/Volume-7/Laser-Pointer.html
15h
comment Why can't incoherent light be collimated as well as laser light (e.g. in a laser pointer)?
@Rocketmagnet i have edited
15h
revised Why can't incoherent light be collimated as well as laser light (e.g. in a laser pointer)?
correction after comments
1d
answered Why can't incoherent light be collimated as well as laser light (e.g. in a laser pointer)?
1d
comment Experiment proving that the Earth is rotating around the Sun
Your ps2 makes it nonsense. If you cannot watch the sky how do you know the sun exists?
1d
comment What is the physical meaning of reduced mass?
"In physics, the reduced mass is the "effective" inertial mass appearing in the two-body problem of Newtonian mechanics. It is a quantity which allows the two-body problem to be solved as if it were a one-body problem." en.wikipedia.org/wiki/Reduced_mass . I do not think that you are expressing well the problem. strings tie, do not stick; do you have a link showing the set up?
1d
comment Why is electrical energy so difficult to store?
@justin The word fall in the slide means thewater-falls of arizona. not the fall of leaves in autumn
1d
comment Why is electrical energy so difficult to store?
sunlight pump water up to waterworks above to the lakes that feed hydroelectric generators to store the excess energy for when it is required. Electricity can only be stored in batteries as I discuss in my answer. The energy can be transformed to another type of energy and recovered when necessary.