Question

Consider the circuit shown in the diagram below. Before the switch is closed, both capacitors are uncharged.


Consider the circuit shown in the diagram below. Before the switch is closed, both capacitors are uncharged. 

image.png

Immediately after the switch is closed, what is the amount of current supplied by the battery?

Assuming the switch remains closed for a long time, which capacitor will be the first to reach 95% of its final charge level?  

What is the time constant for charging this capacitor?

1 1
Add a comment Improve this question Transcribed image text
Answer #1

A) i = 9/90 + 9/30 + 9/60 = 0.55A Answer

B) tow of 2micro F capacitor (t1) = 90*2*10^-6 = 180*10^-6

tow of 4.5 micro farad(t2) = 30*4.5*10^-6 = 135*10^-6

=> So 4.5 micro F will charge first.

B) time constant = 135*10^6 sec Answer

> FURTHER EXPLANATION:
A) Immediately after the switch is closed, the capacitors still have a voltage of 0 since they have not had time to charge up. Thus, you can neglect them and calculate the current as usual by summing the resistors and dividing the voltage by it.
Req = 1/(1/R1 + 1/R2 + 1/R3) = 16.36 ohm
V = 9 V
V = IR ----> I = V/R = 9/16.36 = 0.55 A

B) Once the switch is closed for a while, capacitor 2 receives the most direct path of current thus will reach 95 % of it its final charge the fastest.

C) the formula for the time constant is t = RC. ----> t = (R2)(C2) = (30)(4.5E-6) = 135 microFarads

ISuckAtPhysics Tue, Feb 22, 2022 6:07 PM

Add a comment
Answer #2

A) Immediately after the switch is closed, the capacitors still have a voltage of 0 since they have not had time to charge up. Thus, you can neglect them and calculate the current as usual by summing the resistors and dividing the voltage by it. Req = 1/(1/R1 + 1/R2 + 1/R3) = 16.36 ohm V = 9 V V = IR ----> I = V/R = 9/16.36 = 0.55 A 


B) Once the switch is closed for a while, capacitor 2 receives the most direct path of current thus will reach 95 % of it its final charge the fastest. 


C) the formula for the time constant is t = RC. ----> t = (R2)(C2) = (30)(4.5E-6) = 135 microFarads

answered by: ISuckAtPhysics
Add a comment
Know the answer?
Add Answer to:
Consider the circuit shown in the diagram below. Before the switch is closed, both capacitors are uncharged.
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for? Ask your own homework help question. Our experts will answer your question WITHIN MINUTES for Free.
Similar Homework Help Questions
ADVERTISEMENT
Free Homework Help App
Download From Google Play
Scan Your Homework
to Get Instant Free Answers
Need Online Homework Help?
Ask a Question
Get Answers For Free
Most questions answered within 3 hours.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT