Homework Help Needed

Thread Starter

ace2015

Joined Oct 24, 2017
15
A current I Amps flows through a capacitor at time t seconds is given by:

I=#(1-e^((-t)/τ))

where the time constant τ is 0.8 seconds. Determine:


(i) The current
after (12 + ∆) seconds.

(ii) The time taken for the current to reach (8 + ∆) amps

ACE_Q3.png
 

MrAl

Joined Jun 17, 2014
7,956
Sorry I am new to this site, this is my first post.

Do you know how I can put this in the home work section?
Hi,

Bertus moved it for you :)

Now, what does your number symbol mean in your post "#" is that the voltage or current or something else ?
Maybe you could rewrite that in a more clear form.
 

bertus

Joined Apr 5, 2008
21,140
Hello,

Do you mean 3 instead of the # ?
Can you show your attemp to solve the problem?

Bertus

PS I revomed some posts that are not needed anymore.
 

Alec_t

Joined Sep 17, 2013
11,870
Welcome to AAC!
We can help you, but don't do the homework for you.
Are there any constraints on Δ?
Show us your best effort.
 

Thread Starter

ace2015

Joined Oct 24, 2017
15
Thanks for moving it for me.

I am totally perplexed by this problem.

As far as I know # is an unknown number that needs to be worked out. It is written as that in my assignment question.

Bertus, you are a genius yeah it's a mistake by my college it is supposed to be 3 definitely.

I will get back to you if I need any more help I should be able to work this out now knowing that the college made a typo.

Best regards.
 

WBahn

Joined Mar 31, 2012
26,398
My guess is that Δ might either be an independent variable (though it is two different parameters since one is a time and the other is a current) or it might be a student-dependent parameter so that each student is working a different problem.
 

RBR1317

Joined Nov 13, 2010
603
Do you get extra points for realizing that there is no physical circuit where the current through a capacitor begins at zero and rises to some constant value (beyond 5τ)?
 

MrAl

Joined Jun 17, 2014
7,956
Do you get extra points for realizing that there is no physical circuit where the current through a capacitor begins at zero and rises to some constant value (beyond 5τ)?
Hi,

Yes, this would normally be I*e^(-t/tau) unless they want the student to just take it verbatim.
 
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