+128474 I = (V/R)(1-e^t) multiply both sides by R / V
l (R/V) = 1 - e^t add e^t to both sides and subtract l ( R/V) from both sides
e^t = 1 - l (R / V) take the natural log of both sides
Ln e^t = Ln ( 1 - l (R / V) ) and by a log property, we can write
t * Ln e = Ln ( 1 - l (R/V) ) and Ln e = 1...so we have
t = Ln ( 1 - l (R/V) )
