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Topic: capacitor equation solution not working
Replies: 7   Last Post: Jun 22, 2011 6:33 AM

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Posts: 1,448
Registered: 11/3/08
Re: capacitor equation solution not working
Posted: Jun 17, 2011 5:06 AM
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Surely that is NOT your code; it has at least four misspellings and two
fatal syntax errors -- == where you need = (as in Soleq = ...) and the
comma before [[1]].

If you ran that code, you'd see error messages, not just a constant plot.

This works, however:

i[t_] := If[t < 10 || t > 60, 0, 1]
eq = v'[t] == i[t]/c;
c = 1;
soleq = v[t] /. First@NDSolve[{eq, v[0] == 0}, v[t], {t, 0, 100}];
Plot[soleq, {t, 0, 100}]

I'd also suggest THIS for the first line:

i[t_] := Boole[10 <= t <= 60]


On Thu, 16 Jun 2011 23:09:13 -0500, J and B <> wrote:

> I am trying to solve a very simple circuit, one that has only a
> capacitor in
> it. What am I doing wrong? The final graph should show that the
> capacitor
> has discharged, but its staying constant. I have current starting at
> t=10
> and ending at t=60.
> I hope I have used the correct way to put in my code, I am using a new
> computer and I having trouble with my email program. Any advice would be
> appreciated.
> Thanks
> My code.
> I[t_]:= If[t<10||t>60,0,1]
> Plot[i[t],{t,0,100}]
> Eq=v'[t]==i[t]/c
> c=1;
> Soleq==v[t]/.NDSolve[{eq,v[0]==0},v[t],{t,0,100}],[[1]]
> Plot[soleq,{t,0,100}]


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