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KF5JRV > TECH 14.10.16 12:35l 26 Lines 1623 Bytes #999 (0) @ WW
BID : 3588_KF5JRV
Read: GUEST
Subj: Leyden Jar
Path: IW8PGT<IR2UBX<IW0QNL<JH4XSY<JE7YGF<GB7CIP<N0KFQ<KF5JRV
Sent: 161014/1029Z 3588@KF5JRV.#NWAR.AR.USA.NA BPQ6.0.13
1745 - Electric Force, Capacitor
Leyden Jar is one of the earliest and simplest forms of electric capacitor,
invented independently about 1745 by the Dutch physicist Pieter van
Musschenbroek of the University of Leyden and Ewald Georg von Kleist of
Pomerania. The original Leyden jar was a stoppered glass jar containing water,
with a wire or nail extending through the stopper into the water. The jar
was charged by holding it in one hand and bringing the exposed end of the
wire into contact with an electrical device. If contact was broken between
the wire and the source of electricity, and the wire was touched with the
other hand, a discharge took place that was experienced as a violent shock.
If a charge Q is placed on the metal plates, the voltage rises to amount V.
The measure of a capacitor's ability to store charge is the capacitance C,
where C = Q/V. Charge flows from a capacitor just as it flows from a battery,
but with one significant difference. When the charge leaves a capacitor's
plates, no more can be obtained without recharging. This happens because
the electrical force is conservative. The energy released cannot exceed the
energy stored. The ability to do work is called electric potential.
A type of conservation of energy is also associated with emf. The electrical
energy obtainable from a battery is limited by the energy stored in chemical
molecular bonds. Both emf and electric potential are measured in volts, and,
unfortunately, the terms voltage, potential, and emf are used rather loosely.
For example, the term battery potential is often used instead of emf.
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