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bio website sjbyrnes.com
location Massachusetts
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visits member for 3 years, 11 months
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Apr
13
reviewed Approve Theoretically, is it necessary that if light passes through a glass slab, its intensity should decrease?
Apr
13
comment By what maximum amount can we concentrate sunlight?
The real limit is that you see the sun in every direction, not just the upper hemisphere of directions. Mirrors do exist! The upper hemisphere alone should only give you 25000x, iirc. You must have made an error but I'm not sure what.
Apr
10
answered Calculating the beating length of the directional coupler
Apr
10
answered image transmission through waveguides
Apr
7
revised Blackbody radiation and emissive power
added 330 characters in body
Apr
6
comment How to calculate liquid pressure regardless of the gravity?
Two questions: (1) Do you know n (number of air molecules)? (2) Is the balloon made of a stretchy elastic material like rubber? (If so, the rubber provides almost all the pressure and the water outside can be ignored!)
Apr
6
answered Blackbody radiation and emissive power
Mar
31
answered Unit consistency
Mar
24
awarded  Nice Answer
Mar
23
comment Can a nuclear bomb be used as the power source for a laser beam
See en.wikipedia.org/wiki/Nuclear_pumped_laser but I don't know any details
Mar
18
revised Classical Hall effect when current has neutral charge
add link title and author
Mar
18
answered Classical Hall effect when current has neutral charge
Mar
10
answered Sign convention in optics
Feb
16
comment What is thermodynamic equilibrium?
@EnochArden - The laws of thermodynamics are not axioms handed down by God. They are consequences of statistical mechanics, just as all macroscopic laws of physics can be derived from microscopic starting points. See any statistical mechanics textbook for detailed derivations.
Feb
16
comment What is thermodynamic equilibrium?
@EnochArden - The velocity distribution of a gas is macroscopically measurable - look at doppler shifts of spectral lines for example - as is whether light satisfies a blackbody distribution etc. I take the Boltzmann distribution as a starting point: P~exp(-E/kT). There's a letter "T" in that formula, it's a parameter, and everybody refers to this parameter as "temperature". That's all I mean by "temperature", there's nothing circular there.
Feb
16
answered What is thermodynamic equilibrium?
Feb
13
comment Confusing Chemical potential of mixtures
I don't think there is any sensible or useful way to define chemical potential for a liquid mixture. So I would say it has no chemical potential. Lots of things do not have a chemical potential: The color orange, beauty, etc. :-D Chemical potential is a useful concept to the extent that something maintains its identity in different environments, and is usually (or always) conserved, loosely speaking. So it's a very useful concept for atoms or molecules, but not really for a liquid mixture, since the composition can easily and smoothly change.
Feb
12
comment Confusing Chemical potential of mixtures
What is "chemical potential of the total fluid"? I suspect that there is no such thing.
Feb
4
comment Probability of fluorescence: matching of binding energy and incoming radiation energy?
The binding energies are given by the "K edge", "L edge", etc.
Jan
29
answered Why are $2\pi$ factors included in the definition of the reciprocal lattice?