Simple Electrical Modeling Question (w/ only C and L)

AI Thread Summary
The discussion focuses on deriving a differential equation for a circuit involving a capacitor (C) and an inductor (L) with variables vin and vout. The user initially derived the equation C(d2vout/dt2) + vout = LC(d2vin/dt2) and questioned the legality of separating the derivatives of the capacitor. A response confirmed that breaking up the derivative is valid according to calculus rules. The user expressed uncertainty about whether this method was covered in previous studies. The conversation concludes with reassurance about the correctness of the approach.
Bluestribute
Messages
192
Reaction score
0

Homework Statement


Find a differential equation that describes the circuit that includes only vin and vout as variables.

Homework Equations


C(dvin - dvout)/dt = i
vin - vout = L(di/dt)

The Attempt at a Solution


So the answer I got was:

C(d2vout/dt2) + vout = LC(d2vin/dt2)

My question is, is it allowable to break up the capacitor derivate like that? After substituting in for i, I got:

vout = Ld/dt(C(dvin - dvout)/dt)

Then I broke up the capacitor into vin and vout terms and just rearranged. But I'm not 100% sure if that's legal.
 

Attachments

  • Untitled.jpg
    Untitled.jpg
    7.6 KB · Views: 397
Physics news on Phys.org
Bluestribute said:
So the answer I got was:

C(d2vout/dt2) + vout = LC(d2vin/dt2)
That first C should be LC.

A rule of the Calculus says that the derivative of a sum equals the sum of the separate derivatives, so your approach is correct.
 
  • Like
Likes Bluestribute
Woopsie, right. LC

Ok sweet, thanks. I just can't remember something we might have glossed over a few years ago . . . and no one recently has said "You can do this to a derivative". They just sort of do it on their own.
 

Similar threads

Replies
3
Views
3K
Replies
3
Views
5K
Replies
1
Views
3K
Replies
3
Views
2K
Replies
1
Views
2K
Back
Top