This group (s.e.d.) has done that one to death.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Actually, for a real dielectric, I can't swear that it is.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Where will this energy go?
Yep. Distraction.
Wanted to point to the "capacitor paradoxon" when an uncharged cap is switched parallel to a charged cap. But you know anyway.
w. ================================================= Temperate changes - metal expands or contracts - gap between plates changes. For an air dielectric tuning capacitor, area between plates also changes.
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Why would you say that? The question was about specific heat, which means the amount of energy supplied to generate an incremental temperature change. Here, the presumption is that the flow of energy in or out of the system is what has generated that temperature change, and in the process also changes the capacitance.
Assuming that there is no loss due to leakage, it is absurd to state that the stored energy changes - neither a temperature increase nor a temperature decrease could possibly increase the stored energy.
te
oops, temperature is energy! The thermal energy in the cap is ~1J and the electrical energy is ~10uJ (?) put in your own numbers.)
George H. (for a long time I didn't 'know' that temperature was energy, I could only connect them though this weird entropy factor E=T*S (S=entropy))
Not the same as, but in addition to. If the plates did not flex (an approximation you could base on the small-signal or high-frequency capacitance, where plate deflection is negligible), you would expect that, at some large static potential, the capacitor would store such-and-such, projecting Q = V*C on a straight line (constant C). If you actually perform the experiment, you'll discover the graph of Q vs. V bends up, i.e., C goes up with voltage, storing much more charge at that "large static potential". The difference is the excess energy consumed by deflecting the plates that distance, and that difference is exactly the amount of mechanical energy*.
*Average. The real world has rate losses (ESR, damping of the springy plates, etc.) and static losses (hysteresis of the spring, dielectric, etc.), so the actual zero-to-one integral may be higher than the one-to-zero path. If you obtain a loop in the Q vs. V plot, draw a straight line through the diagonal corners and see how that compares.Tim
-- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
No imbecile, the datasheet for a capacitor tells user about the capacity available versus environmental changes, ie the temperature of the component, the capacitor, dielectric and so on.
ww.highlandtechnology.com jlarkin at highlandtechnology dot com
So I was showing this (figure 1.) in JL's link, to my boss this morning.
He noticed that the temperature scale was in C... I was reading in K!
So it turns out those big heat capacity spikes are the solid-liquid phase transition. (The yokes on me :^)
George H.
Yes, as others have replied, it would be different. A simpler system, the common rubber band, is similar: a stretched rubber band has lower heat capacity than a relaxed one. Grab a rubber band, apply to lips for quick temperature check. Then stretch it, apply to lips again (it gets hotter). Let it stay stretched, until it approaches room temperature, and then relax it. It gets cooler than room temperature.
So, you can imagine a system that acts as a heat pump using the charge-dependence of the capacitor's specific heat. Rube Goldberg or Heath Robinson can sketch out the details...
there's that thermoaccoustic cooler, perhaps a thermally active capacitor could be incorporated
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