You are Here: Home >< Physics

# Discharging capacitors? Watch

1. I have a discharging capacitor connected to 2 power rails (6V and 0V) The capacitor has a value of 100 micro farads and the resistor in parallel with is has a value of 1.3 mega ohms (so a time constant of 130 seconds.) The question is calculate the time at which Vout=3v (assuming discharging begins at time=0)
I got an answer of 90.1 but I'm not sure if its correct? I'm kinda going from memory for the equations you see thanks in advance
2. (Original post by afc4l)
I have a discharging capacitor connected to 2 power rails (6V and 0V) The capacitor has a value of 100 micro farads and the resistor in parallel with is has a value of 1.3 mega ohms (so a time constant of 130 seconds.) The question is calculate the time at which Vout=3v (assuming discharging begins at time=0)
I got an answer of 90.1 but I'm not sure if its correct? I'm kinda going from memory for the equations you see thanks in advance
t1/2 = CR Ln 2
Obtained from exponential decay formula after taking logs.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: April 13, 2013
Today on TSR

### Falling in love with him

But we haven't even met!

### Top study tips for over the Christmas holidays

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.