General form:

$$\int_{0-}^{\infty} f(t) e^{-st} dt$$


Note: s = $\frac{1}{time}$ and is complex. Why? Because the inverse of time is frequency! The limit $0-$ is there for the Dirac impulse function at time 0.


Also consider the step function, $1/s$. Differentiate what do you get? 1. Dirac impulse function!!!


[[Worked Example RC Low Pass]]