Magic capacitors!

'Special Olympics' wrong.

Ha!

John

Under current ROHS regulations, all capacitors must be defluxed...

Case well presented. Much appreciated.

).

I'd say that this puzzle demonstrates that ideal noninductive, nonresistive capacitors do not and cannot exist in the real world. Had they inductance but no resistance the charge would oscillate infinitely back and forth. Were there resistance, the oscillation would damp and the energy would be dissipated as heat. Allowing neither inductance nor resistance, not only does the oscillation never damp, but it would not even have a finite frequency. The charge would simply oscillate infinitely fast - except that this violates quantum mechanics. So this perfect, ideal capacitor violates QM!

If we wanted to have this noninductive, nonresistive pair of capacitors in a QM system, we'd find that the oscillation frequency was in fact finite. Very high, but finite. The delta-E of 'missing energy' would equal Planks constant * frequency. Large but finite. And the system would decay radiatively. Possibly, in this case of extremely nonphyiscal components, a single photon would be emitted carrying away all this energy.

Had to grind it a few cases. Ding Dang it, take some piano wire and hang it.

My Apologies Don. The resistor always eats half the energy.

The "we" I'm talking about is little kids and grandmothers. [Move this thread to SEB instead of SED? :) ] If we want to explain basic circuitry to the general public, we first need to go over the traditional explanations with a fine tooth comb. Get rid of contradictions, and suddenly E&M stops resembling a black art.

By "electronics texts" I meant the ones aimed at the general public. EE courses have little to do with teaching newbies. "Newbies," as in kids' first introduction to electricity in 4th or 5th grade, or visitors wandering through the physics section of the science museum. What would capacitor operation look like, if we could see the current and voltage? Or "newbies," as in HS grads who never took physics, who forgot algebra after the exam, but now they want to grasp the operation of circuitry while mostly avoiding any encounters with Ohm's law. These concepts are appropriate for books like "Evil Genius Guide To Basic Electricity," or "There Are No Electrons." As you say, for EE undergrads, this Capacitors-store-charge stuff is trivial and almost beneath consideration except perhaps as a trick question on an exam. Unlike with EEs, for a total beginner it's a bit of work and a huge "Aha" to realize that capacitors *don't* store any charge, any more than inductors store charge. (Hmm, the idea of coil/capacitor duality becomes a bit clearer once you realize that both components can accumulate field energy, while neither one stores any charge.)

ation in one sentence.

Nobody notices traditional language which completely violates fundamental physics. I suspect it didn't stand out since we didn't have an intuitive grasp of the difference between coulombs and joules. The math works fine, so we didn't really need it.

Now if undergrad textbooks had used explanations which violate energy conservation, we'd hear no end of ridicule from the physics crowd.

Explain electronics to the general public? You've got to be kidding. The GP drives cars but hardly any understand Newton's laws, much less the rotational versions of same.

When our building was being wired up, I showed one of the electricians a sketch of a triangle with a center-tap on one leg, the basic "stinger" diagram. He said "we don't do that theory stuff." But he sure could bend conduit beautifully; he was an artist.

Teach them COE and some simple mechanics first. My wife wants me to put a windmill on our roof.

John

Exellent idea. Be sure to put a nice induction motor on there so that it can be spinning like mad even when it's dead calm. You'll be the envy of your neighbors.

Does he bother doing the load capacity and balancing calculations?

You really don't want it on the roof the noise will drive you crazy and the local turbulence will not make the turbine work well either. Our present UK Prime Minister had one on his home or was going to until they realised it would be a total disaster when monitored.

A lot of commercial wind turbine in the UK are installed to farm the grants rather than the wind. Few places in lowland England have anything like a strong enough wind to be worthwhile sites.

Snag is that generating capacity scales with the cube of windspeed and they have to feather if it gets too windy. I think the vertical axis Darius rotors are about the nicest looking.

A 6kW unit in a region with average windspeed of 6m/s or more will payback on almost commercial terms depending on future electricity prices and subsidies - toy ones for small yatchs are everywhere now.

A low tech one using a sawn in half 45 gallon drum, alternator and bearings from a car was published around 1970. Offer to build her one of those if pressed....here's a page with details in those arcane "English" units you insist on using.

Regards, Martin Brown

If so, he must do them in his head.

Gosh. Thanks. I'll tell her that.

John

Damn, Johnny! You do a better job of insulting everyone around you than our president does. No, I do not refer to my company president. This is a truly defining moment. Wait! We all already knew this about you , Johnny! Other folks named John dislike you being in their group as you sully the name. That is sad, considering the name and its history. You are the weakest link. Goodbye!

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Then again, you could mechanically couple it to your bed frame. She'd adore that. At least once.

And, spinning even when there's no wind, save a lot more energy.

John