If I = 0 at t = 0, when the switch is closed, it can be
shown that 
, where 
. Again, at 
, the current will have yet to
undergo 37% of its full change, or have already accomplished 63% of its full
change
A sketch reveals this information.
In each case, if 
is determined by measurement, L or C can
be determined, if the circuit resistance is known.
[ Purpose | RC Circuit | Square Wave | Measure L| Measure C | Observations]