[Fantasy-Tech] Much Earlier Electrostatics

[Varyon]

Could an electrostatic generator be used for electroplating? That was one of the proposed uses of the so-called Baghdad Battery, when it was thought to be a primitive battery. Another possibility could be an electromagnet - perhaps more one that you use to produce semi-permanent magnets than one that you use directly - but from what I understand, electrostatic generators are generally rather low amperage (if moderately-high voltage), and amperage is what matters for electromagnet strength.

[whswhs]

Originally Posted by Varyon

Could an electrostatic generator be used for electroplating? That was one of the proposed uses of the so-called Baghdad Battery, when it was thought to be a primitive battery. Another possibility could be an electromagnet - perhaps more one that you use to produce semi-permanent magnets than one that you use directly - but from what I understand, electrostatic generators are generally rather low amperage (if moderately-high voltage), and amperage is what matters for electromagnet strength.

A real battery can produce massively more energy output; the energy density of batteries is higher than that of capacitors, which I think is what electrostatic generators amount to.

[Anthony]

Originally Posted by Varyon

Could an electrostatic generator be used for electroplating? That was one of the proposed uses of the so-called Baghdad Battery, when it was thought to be a primitive battery. Another possibility could be an electromagnet - perhaps more one that you use to produce semi-permanent magnets than one that you use directly - but from what I understand, electrostatic generators are generally rather low amperage (if moderately-high voltage), and amperage is what matters for electromagnet strength.

Both electroplating and electromagnets want high currents at fairly low voltages, which isn't the strength of electrostatics. Most practical uses for high voltage/low current involve a vacuum.

[whswhs]

Originally Posted by Anthony

Both electroplating and electromagnets want high currents at fairly low voltages, which isn't the strength of electrostatics. Most practical uses for high voltage/low current involve a vacuum.

I puzzled over this when I was writing GURPS High-Tech: Electricity and Electronics. It didn't seem quite right to say that you have high voltage/low current; for a given system---say, a human body---you have a given resistance, and by Ohm's law higher voltage has to give you higher current, not lower.

What's actually going on with electrostatic systems such as capacitors is that you have only a finite amount of charge; and therefore the high current that goes with the high voltage uses up that charge in a very short time. And when you average the current flow over a longer time---say, the very long span of a second!---the very brief spike of high current and the much longer interval of near-zero current give you a low average current---but the current flow isn't uniform over time. In contrast, with a battery, which can keep renewing the supply of electrons, the current flow can be nearly uniform over time, so the average current is effectively the same as the momentary current; and that average may be higher than the average for the brief electrostatic discharge.