# RLC problem

Discussion in 'Homework Help' started by Furki, Mar 1, 2009.

Mar 1, 2009
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2. ### Furki Thread Starter Member

Mar 1, 2009
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Sorry for being vague but

What is the equation of the curve that joins the peaks of this wave(the one shown in the picture)?

3. ### mik3 Senior Member

Feb 4, 2008
4,846
63
The equation is:

y=Aexp(-bx)

Find the right values for A and b.

4. ### mik3 Senior Member

Feb 4, 2008
4,846
63
From the graph and the equation you have given it has to be:

y=250*exp(-62.5t)

Mar 1, 2009
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6. ### Furki Thread Starter Member

Mar 1, 2009
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Putting t = 26.4ms in y=250*exp(-62.5t) gives 48, it should give 59.2V according to the graph.

btw,
R = 500 ohms, L = 4H, C = 1 uF

7. ### mik3 Senior Member

Feb 4, 2008
4,846
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Then use a point from the graph to calculate A.

8. ### alwayslearning Member

Feb 27, 2008
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You say your plot is marked at 2.5 Volts? It is actually marked at 59.2 Volts.
If you desire to know the value of (t) at 2.5 Volts then specify at which time?

Please specify the initial conditions-I took a guess as -->source is zero, i(0)=0.5 Amps and Vc(0)=377 Volts? Or
di(0)/dt could also have been given instead as 94.24 assumming your A1, A2 are correct?

Last edited: Mar 2, 2009