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resistance in an LRC circuit used to calculate time constant
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To: tesla@pupman.com
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Subject: resistance in an LRC circuit used to calculate time constant
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From: "Alfred C. Erpel" <alfred@erpel.com> (by way of Terry Fritz <twftesla@uswest.net>)
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Date: Sun, 12 Mar 2000 08:56:42 -0700
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Approved: twftesla@uswest.net
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Delivered-To: fixup-tesla@pupman.com@fixme
Hello,
An LRC circuit has three components of resistance; the internal resistance
of the inductor, the internal resistance of the capacitor, and resistance in
the wiring connecting the inductor and capacitor.
The resonant frequency of this LRC circuit is 1 / [2 * PI * SQRT(L * C)]
regardless of the total resistance in the circuit.
a) The time constant of a capacitor is C * R.
b) The time constant of an inductor is L / R.
In the context of this resonant circuit, when you calculate the time
constants of each device, how do you figure R? Is R just the resistance
internal to the device (inductor or capacitor) or do you add up the total R for
the circuit (all three components) to determine R for the equations above? How
do you account for the R in the circuit external to both devices?
Regards,
Alfred Erpel