Re: A Question About A Simple LRC circuit

["John S. Denker" <jsd@MONMOUTH.COM>]

At 02:37 PM 3/5/01 -0500, Robert B Zannelli wrote:

>  My question is, if you have a series LCR circuit is there a simple equation
> which will give the voltage across the resister as a function of time?

Sure.  It's a damped sinusoid
        V(t) = [ v1 sin(omega t) + v2 cos(omega t) ] exp(-k t)

where omega and k are determined by the circuit parameters, and v1 and v2
depend on the initial conditions.  Note that knowing only the voltage V(t)
at t=0 is not a sufficiently-informative initial condition.

See _The Feynman Lectures on Physics_ volume 1 chapter 24 ("Transients").

> If we have a simple RC series circuit and we apply an instantaneous voltage

Terminological nitpick:  I think the proper term is "initial
condition".  The instantaneous voltage is something else.