Consider the circuit represented in a) where C1=9,31 nF, R1=138,8 KΩ and I1=2,0 mA.

Consider circuit b) and the values for Rth and Vth previously obtained.

It is known that the transient response of the voltage in the capacitor will be given by 

Vc_trans(t)= A. e^s.t

 Please give the value for parameter s. 

Hint: please have in mind that C1 is in nF and the resistors are in KΩ