Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

how to integrate this ?

Status
Not open for further replies.
E

engr.waqas

Full Member level 3
Joined
Jul 21, 2009
Messages
172
Helped
13
Reputation
26
Reaction score
10
Trophy points
1,298
Location
karachi,Pakistan
Activity points
2,342
df.JPG
Please see attached picture.
where C=0.001 and i(t)= sin(1000 * 2 PI t )
also i(t)=0 for t<=0
 

Dear engr.waqas
Hi
What is your problem , exactly ?
Best Wishes
Goldsmith
 

Hi
Mr.goldsmith
I am doing an online course where I have to find this integration, the issue is after so many professional years of job , I don't remember integration rules :)
 

There is some error in this because the answer is not being accepted by system.
also the link you told does not cover my case :(
 

engr.waqas,

Why don't you tell us what you think the answer is, and then we will tell you if you are correct.

Ratch
 
I don't know the answer :) I am simply putting my answers in a software which is indicating answer is wrong .
 

engr.waqas,

I think you had better show us how you arrived at your answer so we can critique it.

Ratch
 

My answer is
-cos (2000 * PI * t ) / (2 * PI ) + C

which is again wrong :( but I'm sure it is very close to true answer
 

engr.waqas,

What is "C" in your answer? Is it the 0.001 capacitor?

Ratch
 

No C is a constant from integration which in this case is given as 0. But his answer omits C (Farads).
Perhaps try various ascii versions of my answer given twice previously
 

SunnySkyguy,

No C is a constant from integration which in this case is given as 0.
Click to expand...

Then perhaps he should use a different symbol to represent the constant of integration. But why is there a constant of integration when a definite integral is being evaluated?

Ratch
 

To be integrable over an infinite intervall, the integrated function must converge, but sin(t) doesn't. Either there is a typo in the problem or it's insolvable.

P.S.: The said problem formulation makes no sense, r or it's mathematically incorrect:
i(t)= sin(1000 * 2 PI t ) also i(t)=0 for t<=0
Click to expand...

If you mean i(t)= sin(1000 * 2 PI t ) for t > 0, then you should write it clearly. Also you can change the integration interval to 0 to t.
 

Fvm,

To be integrable over an infinite intervall, the integrated function must converge, but sin(t) doesn't. Either there is a typo in the problem or it's insolvable.
Click to expand...

No typo, everything needed to solve the problem is given.

P.S.: The said problem formulation makes no sense, r or it's mathematically incorrect:
Click to expand...

The given conditions were that i(t)=0 for t<=0 . So from -∞ to zero, the integral evaluates to zero. Then all we have to do is evaluate (1/C)*∫(sin(2π1000t)dt from 0 to t, that is easily found to be (0.5*(1-cos(2000*π*t)))/π .

Ratch
 
  • Like
Reactions: FvM

    FvM

    FvM

    Points: 2
    Helpful Answer Positive Rating
engr.waqas said:
My answer is
-cos (2000 * PI * t ) / (2 * PI ) + C

which is again wrong :( but I'm sure it is very close to true answer
Click to expand...

Because you forget that -cos(x) is the primitive of sin(x), isn't the integral between 0 and t

\[if\;P'(t)=f(t)\;\; then \int_{0}^{t} f(t)\;dt = P(t) - P(0)\]



\[\int_{-\infty}^{t}i(t)\,dt = \int_{0}^{t}i(t)\,dt\] because i(t)=0 if t<=0

Then
\[\frac{1}{C}\int_{0}^{t}\sin{\omega} t\;dt = \frac{1}{{\omega},C} \left( \left( -\cos{\omega} t \right )-\left(-\cos{\omega}0 \right \,)\right )=\frac{1}{{\omega}\,C} \left(1 -\cos{\omega} t \right )= \frac{(1-\cos{(2000\pi\,t)})}{2\pi}\]
 
  • Like
Reactions: FvM

    FvM

    FvM

    Points: 2
    Helpful Answer Positive Rating
I agree with _eduardo_ , I have the same answer for that in tegral which is the most true one if " i(t)=0 if t<0"
 

7@rB,

I agree with _eduardo_ , I have the same answer for that in tegral which is the most true one if " i(t)=0 if t<0"
Click to expand...

I would think you also agree with my answer in post #15, because it is the same one. How is one integral more "true" than another if they are the same?

Ratch
 

The accepted right answer is
(1-cos(2000 * PI * t))/(C*2000 * PI)
But I dont know from where it came ? :) can someone tell me?
 

It's the same solution, that has been derived by Ratch and Eduardo.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top