# Integrating Current-Voltage Relationship for a Capacitor

1. Jan 18, 2007

### vg19

1. The problem statement, all variables and given/known data

To find the voltage-current relationship of a capcitor, integrate both sides of
i = C(dv/dt)

3. The attempt at a solution

In the book they say, v = (1/C)(The Integral from -tve infitity to t) of i dt.

or

v = (1/C)(The Integral from tnot to t) of i dt + v(tnot)

I am trying to understand why they integrated from negative infinity. Why not start the integration at 0. I also do not undersstand in the second equation where the + v(tnot) came from.