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comment A problem of missing energy when charging a second capacitor
Agreed with @OlinLathrop. Circuit theory allows us to use "ideal" elements only as far as it doesn't fall into a paradox (two different current sources in series, two different potential sources in parallel). Then an "ideal short circuit" must be be recognized as at best ideal inductor: if for no other reason charge carriers have mass. Sure there are radiative losses, but the OP doesn't seem concerned that eventually the energy will dissipate in a real system. Instead the energy in the magnetic field from the moving charge becomes static charge in the capacitors.
Apr
7
comment Drying clothes with the sun's heat, without any air
@JoeTaxpayer I thought the answer was a resounding no, but the energy to create a 7 cu feet vacuum against the atmosphere is only 5 watt hour (!). But don't forget you need to keep "replenishing" the vacuum as the water sublimates and pumps are inefficient. Still, it's not obvious that it wouldn't work. It probably is, however, far to expensive to build a vacuum dryer.
Apr
7
comment Why is there a negative sign in front of the optical wave?
Missing $i$ < corrected. Thank you for your other comments. Although, for unsymmetrical signals (I'm speaking generally, not specifically about optics), isn't the sign of the $\omega$ relevant? (Since $exp(jx) = cos(x) + jsin(x)$ and $sin(-x) = - sin(x)$)
Apr
7
comment Why is there a negative sign in front of the optical wave?
I took optics ten years ago. I asked the question because I was reading a paper that wrote $U = U_{o}exp(-j\omega t)$ for vacancy concentration. I'm implementing the paper's model in a program, and that negative sign makes a huge difference (and is welcome). But I can't just add a negative sign in just because I like it. I wanted to know the implications of the negative sign so I can figure out where in my own model I have implicitly assumed my that concentration wave is $U=U_{o}exp(-j\omega t)$
Apr
7
comment Why is there a negative sign in front of the optical wave?
I took optics ten years ago, I forgot a few details in the meantime. So I can't honestly say if there was anything explicitly in the question about direction of travel.
Apr
7
accepted Why is there a negative sign in front of the optical wave?
Apr
7
awarded  Yearling
Apr
7
revised Why is there a negative sign in front of the optical wave?
added 4 characters in body
Apr
7
comment Why is there a negative sign in front of the optical wave?
I didn't forget the imaginary unit - it's not a plane wave without it. I remember asking the TA specifically about the negative sign, and being told the negative had to be there.
Apr
7
revised Why is there a negative sign in front of the optical wave?
added 3 characters in body
Apr
6
asked Why is there a negative sign in front of the optical wave?
Feb
24
answered My physics teacher gave us this equation $v= -3 +3t$
Feb
23
comment Why isn't temperature measured in Joules?
What I mean is that it's wordy to say T in Joules, in the same manner that it is wordy to give an airplane's airspeed in milimeters/year. eV, an energy unit like Joule, would be better and I would be the first to welcome it so we can start dropping R and k.
Feb
3
comment Where did earth's electric charge come from?
You're not measuring a charge with a voltmeter, you're measuring the potential difference due to a current of charge. The Earth can be neutral and still have ground currents.
Dec
11
revised Computer cooling with dry ice, ideas and question; thermodynamics
added 204 characters in body
Dec
11
comment Computer cooling with dry ice, ideas and question; thermodynamics
@Aron I modified the answer accordingly. However, if we take the question/answer too seriously, it should be re-posted on a chemical engineering exchange. Any extreme cooling will cause condensation, although the ethanol in my solution should absorb quite a bit of water.
Nov
8
awarded  Necromancer
Oct
22
comment When a planet is heated through gravitational pull, where is the energy taken from?
I don't think Jupiter would stop rotating. For one, it would violate the conservation of angular momentum. Instead, the Jupiter's rotation and the moons' orbits and rotations will become such that rate of change is zero. Of course, this ignores that Jupiter is a body in the solar system.
Sep
18
comment How do you add temperatures?
It would appear that you were meant to use an interpolation, but I'd ask your colleagues to confirm this (for example there might be a specific type of interpolation that is required)
Aug
27
awarded  Yearling