Transient RC Circuit (got answer in s but not in t-domain)

[jaus tail]

Homework Statement

Homework Equations

Vc = ( Initial Voltage - Final Voltage ) e^(-RC/t) + Final Voltage

3. The Attempt at a Solution
I got the answer through Laplace but am not getting through time domain analysis.
Given q across C is 2.5mC
C = 50micro F
q = CV
So V = 50V
Initial voltage = 50V
Final voltage = 100V since C will be open circuit on steady state.
Req = 10 ohm
Ceq = 50 micro F
RC = .0005
1/RC = 2000
So applying the underlined formula I get Vc = ( 50 - 100) e^(-2000t) + 100
Ic = C dV/dt = 50 micro times (-50 * -2000) e^(-2000t)
Ic = 5e^(-2000t)

Book answer is A.

 

[rude man]

The polarity of the capacitor initial voltage is not indicated so you can't solve the problem.

 

[jaus tail]

Oh yeah. I tried with polarity of lower plate positive and got answer in time domain. Thanks.