voltage on a ***, discharging
v = v0e^(–t/RC)
R is resistance in ohms,
C is capacitance in farads
t is time in seconds

1.10 = 75e^(–10/RC)
e^(–10/RC) = 0.014667
–10/RC = -4.222
RC = 2.36seconds

v = v0e^(–t/RC) = 75e^(–20/2.36) = 0.0156 volts

More Answers

V(t)= Vo( e -at )
Vo = 70 and V(5.0) = 1.10
we have
V(t) / Vo = e-at
(a) What is the time constant of the circuit?
-at = ln(V(t) / Vo ) plugingin we have
-a (5.0) = ln(1.10 / 7 )
a = - ln(1.10 / 70 ) /5.0=
a = 0.83063
(b) What is the potential difference across the capacitor att = 20.0 s?
now since we know a
V(20.0)= 70( e -0.83063 x 20.0 )
V(20.0)= 4.26 x 10^-6 V