alt.engineering.electrical

In article ,
Steve wrote:

> I've asked inductor questions before and never fully understood the
> answers.
>
> First of all, I took calculus and learned derviatives as: X^3 d/dx = 3X^2.

Certainly a better way of writing this is: d/dX (X^3) = 3x^2.
>
> The voltage across an inductor is given by: v= (L) di/dt
>
>
> I'm unsure how to take the derivative of that formula because there is a di
> in the numerator.
>
> I understand it can be said as delta i / delta t. But this would be in the
> case of t approaching 0 or a linear change in current; . a linear ramp.
>
>
> What if I had a poteniometer that was changing at an acceleration rate
> instead of a linear rate? Then my i would not be linear, it would be
> curved.
>
>
> What if I wanted to know the current at exactly X seconds not using a delta
> assumption?
>
>
> Any calculus assistance will be appreciated.
>
> . I am aware this formula can be used in Diff EQ and a formula will show
> the voltage at every point in time.

Your misunderstanding is mostly of the physics. The mathematical aspect
is not so important. In uyour context, I presume, you need to have a
specific functional form for i. Not to be original, suppose i(t) = t^3
and L = 2 henries, what would v be as a function of time?

Bill