# Current formula question

1. May 4, 2008

### complexc25

I know I(t) = Io [1 - e-t/t ] is the formula to calculate the current in an RL circuit, however i have no clue what "e" stands for. Can someone give me an insight?

2. May 4, 2008

### Mapes

e is the exponential function: here, it means $\mathrm{exp}(-t/\tau)$, where $t$ is time and $\tau$ is a characteristic time constant.