- #1

Mohamed Abdul

## Homework Statement

1. The characteristic decay constant for a capacitor C discharging through a resistor R is the product of R times C. If the initial voltage at time t = 0 is Vo = 13Volts and what is the voltage at time t = 2RC?

2. A capacitor C = 9microFarads is charged from 0Volts to 7Volts through a resistor R = 39kOhms. How much time will it take to charge to 59% of full voltage? Express your answer in milliseconds.

## Homework Equations

Charging => V = Vo(1-e^-t/Tau)

Discharge => V = Vo(e^-t/Tau)

Tau = RC

## The Attempt at a Solution

For the first question I plugged in 2RC for time into the discharge equation, and canceled the RC with Tau to get 13*(e^-2) = 1.76

For the second question I'm thinking of plugging the same variables, but am unsure of what my initial and final voltages are. I thought they could be 0 and 7, but if that was the case V would equal 0 because Vo would equal 0, which I don't think is the case.