1. The problem statement(adsbygoogle = window.adsbygoogle || []).push({});

http://s685.photobucket.com/albums/vv212/dewdr0p714/?action=view¤t=5circuittakehometest1.jpg

1) Determine the equivalent capacitance of the circuit

2) How many RC time constants are needed for the charge on the capacitors to reach 75% of their final charge?

2. Relevant equations

q= q0 (1 - e^-t/RC)

q=CV

3. The attempt at a solution

I tried to find the equivalent capacitance....this was my method but I am not sure if it is correct.

Equiv Capac = (15*10^-6)(10*10^-6) + (10*10^-6)(10*10^-6) + (15*10^-6)(10*10^-6) / (10*10^-6) + (10*10^-6)

Equiv Capac = 20*10^-6 Farads

For the RC time constants question, I think I need the capacitance to be able to solve it and with the capacitance that I got, I could find q thru the equation q=CV....after that I am unsure about how to proceed with question #2. Does the q get inputted for q or q0?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Capacitance of circuit & RC time constant

**Physics Forums | Science Articles, Homework Help, Discussion**