x Turn on thread page Beta
 You are Here: Home >< Physics

# Physics Unit 4 - Capacitors Help!!! watch

1. Hey guys. Studying for the paper tomorrow. Can you help me with this question?

2. (Original post by Sandy_Vega30)
Hey guys. Studying for the paper tomorrow. Can you help me with this question?

You have to use the formula Qx 0.5 = Q x e blah blah
I tried sending the answer in a picture but it doesnt let me
3. Hi. If you use the equation Q = Q0 x E ^-t/RC and rearrange you can get D as the answer. i've attached the working I did:
Hope this helps! If you're unsure about any bit feel free to ask!
4. (Original post by VeeDubSpecs)
Hi. If you use the equation Q = Q0 x E ^-t/RC and rearrange you can get D as the answer. i've attached the working I did:
Hope this helps! If you're unsure about any bit feel free to ask!
or remember the answer is referring to half life of the capacitor kinda thing which is 69% so 5x69% gives you 3.45 which is 3.5 (2sf).
5. (Original post by raman_17)
or remember the answer is referring to half life of the capacitor kinda thing which is 69% so 5x69% gives you 3.45 which is 3.5 (2sf).
That's a good point! Hadn't thought of that
6. (Original post by VeeDubSpecs)
Hi. If you use the equation Q = Q0 x E ^-t/RC and rearrange you can get D as the answer. i've attached the working I did:
Hope this helps! If you're unsure about any bit feel free to ask!
Thank You!! Understood!!
7. (Original post by raman_17)
or remember the answer is referring to half life of the capacitor kinda thing which is 69% so 5x69% gives you 3.45 which is 3.5 (2sf).
The half life of a capacitor is 69%? And why do you multiply it by the time constant?
8. (Original post by Sandy_Vega30)
The half life of a capacitor is 69%? And why do you multiply it by the time constant?
As its referring to "time taken" to reduce to half which is the half life of the capacitor

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: January 20, 2016
Today on TSR

### Happy St Patrick's day!

How are you celebrating?

### Stay at sixth form or go to college?

Discussions on TSR

• Latest
Poll
Discussions on TSR

• Latest

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