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Oct
28
revised Perceived acceleration in an artificially modulated gravitational field
added argument
Oct
28
reviewed Approve Symmetric potential and the commutator of parity and hamiltonian
Oct
28
comment Perceived acceleration in an artificially modulated gravitational field
@Hypnosifl, I think the thing about tidal forces is you need (at least) two particles separated in space-time, and the tidal forces decrease with the separation. (That's why I specified a "test particle".) You're right that the proverbial astronaut falling into a black hole will be spaghetti-fied.
Oct
28
answered Perceived acceleration in an artificially modulated gravitational field
Oct
28
comment Perceived acceleration in an artificially modulated gravitational field
@DavidHammen, more's the pity. It seems like one of those things that just ought to be true (imho).
Oct
28
comment Perceived acceleration in an artificially modulated gravitational field
Mach's principle!
Oct
27
reviewed Approve How many atoms exist within a continuum body?
Oct
27
comment Reading the Feynman lectures in 2012
@Physikslover, I'm not recommending Mead's monograph; as Ron Maimon mentioned, it wasn't particularly successful. I think the point was to "motivate" Maxwell's equations by showing how they emerge from something simpler. (Ron Maimon may have a different perspective; my default posture is to defer to him!)
Oct
27
reviewed Approve How many atoms exist within a continuum body?
Oct
27
reviewed Approve How would one detect antihydrogen in the universe?
Oct
26
comment what could generate a high-pitched whine in electronics where the frequency depends on the current?
@user6972, ok, got it.
Oct
24
comment what could generate a high-pitched whine in electronics where the frequency depends on the current?
@user6972, I concur about power supply switching frequencies in general; it all depends on the supply. However, high voltage supplies tend to run at lower frequencies because of the high effective capacitances presented by the high voltage transformer. Moreover: 1) I claim magnetostriction as part of the power supply, since the transformer is an element in it. 2) a steady sound usually requires a driving signal at the same or a related frequency, so just saying "magnetostriction" without identifying an underlying frequency source is not an answer, imho.
Oct
24
comment Physical explanation for capacitive circuit
@IncnisMrsi, I take your point that my answer could be elaborated. Would you care to add an answer that does so?
Oct
24
awarded  Revival
Oct
24
comment How does current flow from the emitter, through the base and to the collector in a NPN transistor?
@IncnisMrsi, updated per your recommendation. Thanks!
Oct
24
revised How does current flow from the emitter, through the base and to the collector in a NPN transistor?
specified "current gain" per comment.
Oct
24
comment Reading the Feynman lectures in 2012
The potential-based approach to EM you mention may be "Collective Electrodynamics" by Feynman's student Carver Mead: en.wikipedia.org/wiki/Carver_Mead . PS: I recall you writing favorably of Steven Frautschi's S-Matrix book. I saw him recently; in retirement, now 80, he has re-invented himself as a teaching assistant, and won Caltech's Feynman Prize for Excellence in Teaching this year. When I mentioned his S-Matrix work being cited here, he ducked his head and said, "Well, that was a long time ago..."
Oct
23
comment Reverse bias P-N junction
@IncnisMrsi, 1) Thanks, my wording was poor; I've attempted to improve it. (I meant excess in comparison with the unbiased junction.) 2) I concur. Apparently this ideal diode characteristic works fairly well in germanium diodes (because $I_0$ is larger than for silicon?), but in Si, other mechanisms, like carrier generation in the transition region, cause the reverse-bias current to vary with voltage.
Oct
23
revised Reverse bias P-N junction
clarified wording
Oct
23
comment Homemade salad dressing separates into layers after it sits for a while. Why doesn't this violate the 2nd law of thermodynamics?
After way too much time, I see that my criticism was incorrect. Apologies for my confusion...