The voltage across the plates of a capacitor at any time t seconds is given by V=Ve -t/CR, where V,C and r are constants. Given V = 300 Volts, C =0.12*10-6 F and R = 4*10 6 ohms

Question

The voltage across the plates of a capacitor at any time t seconds is given by V=Ve -t/CR, where V,C and r are constants. Given V = 300 Volts, C =0.12*10-6 F and R = 4*10 6 ohms 
Find the initial rate of change of voltage
and the rate of change of voltage after 0.5 seconds

Damon · Accepted Answer

I think you probably mean

V = Vo e^(-t/RC)
where Vo is 300 volts and the chrge is discharged through the resistor

here 1/RC = 1/(.12*4) = 2.08
so
V = 300 e^-2.08 t
dV/dt = -2.08(300) e^-2.08 t
= -625 e^-2.08 t volts/second
obviously when t = 0 this is -625
you can put in .5 or anything else for t