RC Circuit Analysis (2 of 8) Voltage and Current

[@veronicas8270]

YOU ARE A GODSEND AND I LOVE YOU. I have been spending weeks learning this, and today, the day before the exam, I finally understand RC circuits. Thank you!

[@stepbystepscience]

Thank you ver much for the great comment. Great that you found the videos helpful.

[@qaisar.sulaiman]

10 years later and this dude is still the G.O.A.T.

[@stepbystepscience]

So nice of you, thanks!!

[@user-ce4zj8jh7k]

I appreciate how you divide the problem up into parts that can act as a checklist to complete the analysis. thank you!

[@May-zp1mr]

The breakdown and the way you make me think of these topics have been more helpful than reading textbook! Thank you!!

[@stepbystepscience]

Glad it was helpful!

[@brittanyalexander726]

This video was incredibly helpful! I am tutoring for physics today and watching your videos was very useful for brushing up on subjects I have not reviewed in nearly a year. Thank you for creating them!

[@yulisxia6510]

This series single handedly taught me rc circuits. Very helpful thank you

[@stepbystepscience]

Great to hear! Thanks for the comment.

[@punny2688]

I just wanted to say you saved me in engineering physics 2, thank you so much!

[@stepbystepscience]

That's fantastic! You're very welcome!

[@boyanatanassov9263]

Hi There, At time-stamp 1:43 Your last statement is: Two things - capacitors are charged and current is running through those two capacitors... Most likely you wanted to say: capacitors are charged and current is running through those two RESISTORS... ;-) Your tutorials are great!!! I LOVE them... I am going over them and taking notes... I have become so good I even started catching the MASTER's miss-spells... ;-) I am sure you meant Resistors... Like in the prior video you said 25 amps instead of 20 amps... It's OK to make a mistake with so much numbers in ones head!!! Cheers

[@brigadooner]

Very helpful. You're truly channeling Sal Khan in these videos.

[@stepbystepscience]

thanks for the comment.

[@TeamRocketFan098]

This is such an informative and great video for the basic understanding of RC circuits. Despite the people complaining that you pronounce capacitor differently, it didn't impede my understanding at all. Great job!!!! You teach better than some college professors :)

[@stepbystepscience]

Thanks for taking the time to write such a nice comment. Glad that you find the videos helpful. You can also see a listing of all my videos by topic at www.stepbystepscience.com

[@sigmabond1289]

nicely explained...you start right from the basics and thats the best part....all the gaps fill up...thanx a ton!

[@stepbystepscience]

You are very welcome. Thanks for watching and commenting.

[@jack002tuber]

Excellent video. A huge chunk of info in ten minutes. Well done.

[@rominhawk3949]

Wow! Really excellent explanation and presentation video, sound, all. Thank you very much. I just found your channel when searching for RC circuit analysis. And what a wealth of information I found. I subscribed right away and will be viewing all that you have presented.

[@stepbystepscience]

Thank you for doing all of that.

[@aayushrijal9077]

i cannot epress how helpful it is for me . i am very thankful to u step by step science

[@stepbystepscience]

Thank you very much for the great comment, glad that you find the videos helpful.

[@rayfields2596]

Here's why I like this video so much. We all get these textbooks in school that show us examples, and our professors try to teach us this subject and another five or more concepts in a 1 hour lecture if that. When you can get a singled out explanation for something like this, it's soo much easier to sink in and understand. Thanks. I have a request though; can you make a video about the Voltages of the Capacitor in an RC circuit and how it changes through 5 time constants?

[@stepbystepscience]

+Ray Fields OK, maybe I will try taking on charging and discharging capacitors in my next videos.

[@stepbystepscience]

+Ray Fields and also thanks for the positive comment!

[@coreylevinson7339]

Thank you for the video. Simple things like 'voltage is the same when in parallel' really clear things up.

[@stepbystepscience]

Corey Levinson You are very welcome, I try to use "regular/simple" language when possible. Thank you for the comment.

[@coreylevinson7339]

You seem very intelligent, so I want to ask you a bunch of questions I've been saving up when studying circuitry. It's a bombardment of questions, though, so you don't need to answer if you don't have the time. I'm taking physics in school so these questions will help me. -why do you not short circuit a battery by touching both ends with your finers? is skin's resistance so high that it essentially breaks the circuit? -what causes death? Voltage or current? -how can birds sit on power lines? -if a capacitor is 10 microfarads, in an RC circuit, then at t=c, where c is a random constant, the capacitor can hold the maximum charge of a 5 microfarad capacitor, maybe later the max charge for a 6 microfarad capacitor, maybe earlier the maximum charge of a 3 microfarad capacitor? -why does a circuit complete itself if you are standing on the ground and you touch a charged conductor that's connected to a battery or transformer on the ground? -is a battery connected to ground if its physically touching the ground or does it need to connect itself to a long metal pipe in the ground? -does voltage come out of the negative or positive side of a battery? -why does emf exist? Why is it important in circuitry?

[@coreylevinson7339]

-how does a capacitor charge if it's not a circuit? -why must a circuit connect back onto itself? I understand its necessary to have a complete circuit oelectrons can flow, but why? -if you have high voltage in a wire, why doesnt a spark form in between a switch? -if a high capacitance capacitor is fully charged, why doesn't a spark form in between? -Why are wires covered in conductors? -what's so good about coaxial cables? -if a resistor has a really high resistance, is it possible to effectively cut off the current, thus breaking the circuit? -is a lightbulb flickering really quickly? I think the answer is no but I dont know. -imagine two circuits each with a battery with potential V. In both circuits there is one resistor. In the fist circuit, the resistor is 1 ohm. In the second circuit, the resistor is 10000 ohms. Which circuit depletes the battery faster? -what happens if a battery is fully charged and you try to charge it even more (i understand this question might have more to do with chemistry than physics) -How does grounding work? Why is it important? -what is bemf?

[@kirankumartuppad5679]

I am very new to this topic.. i found this video is very helpfull for me to understand RC Circuits in a very very basic version

[@stepbystepscience]

Kiran N T Great that is exactly what it is supposed to be.

[@coltonb1352]

This is awesome thank you I was not understanding this in my class but now ive got a much better grasp on it.

[@stepbystepscience]

Great, thanks for the comment.

[@darnaj38]

Thanks. Just a detail, at 2:44 the dimension of your inverse capacitance is 1/uF and not uF.

[@anots9735]

Thanks sir it's very helpful for my IIT JEE exam . Again thank you so much sir ...🙏🙏🙏

[@stepbystepscience]

You're very welcome. All the best!

[@darkknight-xm5cj]

im a little confused on the potential difference isnt the total supposed to be 6? yet the 20ohm resistance is 4V and so is the 2 C branch

[@stepbystepscience]

It is 4 V across both branches because 2 of the volts are used by the 10 Ohm resistor.

[@nooralnasser4588]

I’m really enjoying learning from you, perfect 🥺🦋💕

[@stepbystepscience]

Awesome! Thank you!

[@donnicolaisalonga8816]

your videos are frustratingly good. wow

[@stepbystepscience]

Thanks for the nice comment.

[@dimitrisksylogiannis2172]

in question 2 how is the current through both resistors the same? The current through the capacitors is 0?

[@stepbystepscience]

Because after the circuit have been running for a long time the the capacitors are charged and no current flows through them. Therefore, the two resistors are in series and have the same current flowing through them. Does that help?

[@eshnaroy779]

Thank you so much.... the easy breakdown of the concepts is really helpful..... as rightly mentioned in the comments, you really are a godsend!!!

[@HashemAljifri515]

Best one to explain electric physics

[@stepbystepscience]

Thanks so much!

[@WimpyWarlord]

brother at 1:45 u said current is running through those two capacitors where as u should say across the parallel branch........ well your video helped me a lot. thanks .keep it up.

[@stepbystepscience]

Got it, thanks.

[@cemaldinc6008]

Im Turkish ı understood every word u told its very clear expression thank u

[@stepbystepscience]

Great, thank you very much for watching and commenting.

[@mufakkirhussain2816]

Sir your videos are nice. I want your videos to be shared with everyone. Write long description in your KZbin description title before uploading. It will help people to finding your videos, this is how KZbin search algorithm works. Salam from Pakistan.

[@stepbystepscience]

OK, thanks for the advice. I have made my descriptions longer in my newer videos.

[@westonschwartz2483]

You make these so easy! Applause you

[@stepbystepscience]

Thank you very much.

[@JohnyDays69]

done! I finish it as soon as you finished the video.... yeah I got the same answers. I'm still in shape !

[@stepbystepscience]

Great, thanks for commenting. You can see a listing of all my videos at my website, www.stepbystepscience.com

[@naderhumood]

Sir Great , helpful. And .....nice apprauch. ...👍 I have sent my regards from Bahrain ...

[@stepbystepscience]

Awesome, thank you so much for watching and commenting!

[@EdwinFairchild]

what if there is a resistor between cap 1 and cap 2 are they still treated a "resistors in parallel"

[@Luxcium]

Nice video the first was nice and this one is even better now see ya on the third one

[@TheTheaterThug]

Why are the 10 and 20 resistors in series if theres another place the current can go? Does it only matter if the current has a choice between 2 or more resistors? I guess its still in series even though it could go to the capaciTORs

[@ndeshantiano7905]

Thanks for the video,and please upload more videos!!

[@stepbystepscience]

There are more to come!

[@abelashenafi6291]

hey man ur doing a really great job. i wish i could give u a 1000 likes on my own. all of ur videos especially 3 and 4 are really really helpful. please do more videos on RL and RLC circuits

[@stepbystepscience]

Thank you, very nice if you to say.

[@TuhinKar787]

Easy and simple....you made it so easy....Thanks a lot

[@stepbystepscience]

That is the goal, break everything into manageable pieces. Thank you very much for the comment. You can see a listing of all my videos at my website, www.stepbystepscience.com

[@andrewmitchell4205]

You said in your last video that at t equals infinity the current is equal to zero. In this video you state that we will be assuming that t is equal to zero but then you go on to find current through the R is .2A. I do not understand why I is is not zero.

[@stepbystepscience]

In the first video there is resistor and capacitor in series, after a long time (5 time constant) the the current has been reduced to zero. In this video there is a branch with just a resistor, when the switch is closed the current through the resistor goes to its max right a way and stays there. Does that help? You can see a listing of all my vidoes at www.stepbystepscience.com

[@andrewmitchell4205]

So it is because of the branch with the lone resistor that the current is maintained?

[@stepbystepscience]

+Andrew Mitchell yes

[@zeegh5867]

thanks, learned that Q total = Q 1=Q2 for the capasetors in series. that was helpful information that is essental

[@s3ba5sti4n]

Thanks a lot! Regards from Argentina!

[@stepbystepscience]

You are very welcome. You can see a complete listing of my videos at www.stepbystepscience.com

[@yashorts1259]

Your videos are amazing

[@stepbystepscience]

Thank you so much!

[@matchaicecream6086]

for question 2 why do you have to use the total resistance when it is specifically asking about the current going through the 10 ohm resistor?

[@mrsemifixit]

Could you explain why the lower value capacitor stores more voltage than the 12uf if the charge is the same. Is it due to different internal resistances?

[@RajendraPrasad__Its_my_profile]

Thank you, simple and awesome.. very clean and clear.. A quick question, when your explaining solution for 4th question, the unit of the capacitor is 4uF not 4uC right ??

[@julius64]

Velocity 😁😁😁 it happens when u have more concepts in mind. Cheers

[@stepbystepscience]

Thanks for the comment.

[@patrickzhao9072]

ikr!

[@murphysquint3436]

I found two errors. You said 0.25A at time 4:26 instead of 0.2A. Also, in your equation at time 10:21 you say the charge is 4 microfarad but the equation show 4 microcoulomb. Great lessons, thank you.

[@stepbystepscience]

Thanks

[@Atharv_Nigam]

That solved most of my doubts... great job !

[@stepbystepscience]

Excellent!

[@ndeshantiano7905]

Wow!!!!!! This is so amazing ,i found what i wanted

[@stepbystepscience]

That's wonderful, glad I could help!

[@jegatha123]

7:58 how do we say voltage is 4v isnt it 6v? Can you explain😅

[@stepbystepscience]

Good question, but no, it is 4 V because 2 V get used bay the 10 ohm resistor....right.

[@jegatha123]

@@stepbystepscience ohh.. I got it now Thank you so much sir☺

[@uluyurth]

What would be the time constant for this circuit if there were only one capacitor?

[@ghayadsayegh8367]

but i have a question , in the firrst you assume that the voltage between 10 resistor in 6 and calculate the current then u said that the voltage around the 10 resistor is 2 ,!!!

[@magnusonx1]

My argument here is that, based on my past experiences with circuit analysis, both resistors are not in series (nor parallel). I have been taught that, when there are circuit elements connected between two resistors, they fundamentally cannot be called in series (reference node X and the elements, the 2 capacitors, below it). Since the assumption here states that, in this case, the capacitors are fully charged, would this be an exception? With both capacitors fully charged on the middle wire, can we then say that the 2 resistors are in fact in series? Also, what if the capacitor(s) where not charge, could we still say that the resistors are in series?

[@shine6290]

Man thank you so much for this video! You helped me a ton

[@stepbystepscience]

Happy to hear that, best wishes to you.

[@atsnitsri7258]

the video was very good but only problem for me was the style of speaking but captions resolved it

[@stepbystepscience]

Thanks.

[@sandroch8967]

Very good. Congratulations!

[@stepbystepscience]

Thank you very much!

[@carlosblock]

I really appreciate your video, well explained and very useful. I have a question: Mounting a timer with a 555 I need to know "when" the capacitor is going to arrive to 1/3 and 2/3 of the total voltage. Let's say I have a 9v rail voltage and I want to know how long is going to take for the capacitor to arrive to that voltage with a resistor on serie. I can't find an easy way to do It. Could you help? Thanks anyway and really god Job. Carlos

[@123kkambiz]

Thank you very much for very nice presentation of RC circuit analysis, Can you tell me what program you used for presentation of this video, is it microsoft Power Point?

[@stepbystepscience]

123kkambiz Thank you for the positive comment. The presentation is made with Keynote from Apple.

[@123kkambiz]

Brian Swarthout Thanks again.

[@massinissa9623]

In point x the current will split into two current so current in 10 ohm and 20 ohm not the same?

[@RoyAndrews82]

It's like two voltage dividers... The capacitors in the middle because they're in series reduces the voltage from the voltage divider of the two resistors.

[@markcohen2533]

Really great job with these videos. Thank you for your help!

[@stepbystepscience]

Thank you very much for the comment.

[@VIPULSAINI1]

Thank you very much for this video unbale to find better video then this so simple easy to understand thanks

[@banetch]

very good video, well explained...

[@stepbystepscience]

Thank you

[@krish2nasa]

Excellent explanation, Thank you very much

[@nkosinathimzilikazi]

keep up the good work, your videos are very helping

[@stepbystepscience]

Thanks for letting me know. You can see a listing of all my videos at www.stepbystepscience.com

[@dblevins343]

For question 4 I'm confused. I was able to follow everything up until you said the charge on both capacitors has to be the same since they are in a series. Why is that? I would think the the capacitor with the higher capacitance would hold more charge.

[@stepbystepscience]

For capacitors in series the charge is the same. This video explains it: kzbin.info/www/bejne/e37HoZ56pLKLjqc

[@virtualtreadmillwalknature1488]

Great explanation !!

[@РођакНенад]

very insightful, thanks for making the video

[@stepbystepscience]

You're most welcome, glad it was helpful!

[@visalakshirawat8946]

Very good explanation. It was very useful.

[@stepbystepscience]

+Visalakshi Rawat Thank you for the comment You can see a listing of all my videos at my website, www.stepbystepscience.com

[@1cy1nsanity]

How can the current at time = infinite be the same as the current if there are no capacitors in the circuit? Don't the two capacitors store some of the total charge/current in the circuit?

[@davidmejia-martinez4715]

How come the resistors are in series?

[@stepbystepscience]

Because when the capacitors are fully charged no current flows through that branch, but the current still flows around the outer branch through the resistors and then they are in series. Does that help?

[@NSMQ1998]

You are better than my Doctor come teach us 😭😭😭

[@vuhhhronkia]

at 4:35 i thought that when the capacitor was fully charged, that the resistor would have a no current....

[@judy-chan4536]

only when the resistor is placed among the same branch(or in series) with the capacitors. that's why he kept saying outer branch(the one in parallel with the capacitors, which is the 10ohm and 20ohm resistors).

[@judy-chan4536]

look at the circuit again. previous video has capacitor and resistance in a series. the resistors in this video is parallel to the capacitors.

[@THR1125]

Very clear explanation

[@stepbystepscience]

Glad you think so!

[@mattamunoz1]

at 8:21, you mean 4 micro farods x 4 volts, right??? Also thanks so much for this video, I hate RC circuits and this made sense.

[@stepbystepscience]

+matt munoz Yes you are right, it should be 4 microfarads. Thnaks for noticing and letting me know! You can link to all my videos at my website: www.stepbystepscience.com

[@kiarrapigao8264]

8:00 it’s uF instead of uC. Thanks for the vid!

[@mohdsateria6359]

The total charge over the 2 capacitors is the same for both individual?

[@stepbystepscience]

We don't really say the total charge "over" the two caps....it is really about the charge stored on the capacitors or the potential difference across the capacitors. If their capacitances are different, then the charge and the potential differences will also be different.

[@yashvardhanmalve16]

Thank you so much It helped me a lot......

[@velimirstanimirovic4904]

Thanks for the lesson, nicely presented. Are you still active on U-tube?

[@stepbystepscience]

I am still here, trying to make a video once a week.

[@wronski11]

What would happen if your 10 Ohm resistor was a capacitor. If there was no 20 Ohm resistor, you are just going to charge the capacitors. If the 20 Ohms are there however, would you be charging the capacitors with less current? Under normal circumstances, if the 10 Ohm was replaced with a capacitor, they would be in series and all capacitors will have the same charge. However, I am not sure what will happen if the 20 Ohm is connected in parallel to the 12 uF and the 6 uF. Would it be preventing them to get the same charge as the capacitor which we used to replace the 10 Ohm resistor?

[@stanzinnurboo6487]

Nicely explained.

[@tonoychowdhury2032]

I have a question from the very end of this video.......Shouldn'd the voltage across the 6uF be 4 and 12uF be 2................and together should'nt they be 6 ohms alltogether????

[@stepbystepscience]

Tonoy Chowdhury Sorry but no.

[@tonoychowdhury2032]

Brian Swarthout oh yes my bad...........after charging the v=q/c.............i got mixed up

[@stepbystepscience]

Tonoy Chowdhury No problem.

[@riddhigaikwad3386]

When a capacitor is charged through a DC supply source for infinite time, the final current through it is - (a) Determined by the resistor (b) Half of the initial current (c) Infinite (d) Zero. please reply of this answer sir please 😓

[@anikatasnim8012]

If we calculate this after a long time, then like the previous example shouldn't the current through the 10 ohms be zero? Like if the capacitors are fully charged and the source ran out of power? Then the only source is the equivalent capacitors. why isn't it like that?

[@duharirelilia]

Sir, your videos are very helpful thank you very much but i think you made a mistake the resistors are not in series ,they are in parallel

[@stepbystepscience]

Sorry, I may have misspoken but you should be able to see from the diagram if they are in series or parallel. Thanks for your comment.

[@rabihatut]

after long time the current in the circuit drops to zero. As result the pd across the 10 ohms resistor drops also to zero which means at the end the 2 capacitors are sharing between themselves all of the 6V of the battery. Vxy = 6V in Q4.

[@tylermathison9444]

I'm a little confused. How can the resistors be considered in series when the capacitors separate them?

[@stepbystepscience]

The capacitors do not separate the resistors. Once the capacitors are fully charged, the current continues to flow through the resistors and the current through each resistor will be the same. Therefore the resistors are in series. Does that help?

[@tylermathison9444]

@@stepbystepscience Yes, that makes sense thanks!

[@bichuraj9708]

Nice video and simple explanation

[@stepbystepscience]

Thank you very much. You can see a listing of all my videos at my website, www.stepbystepscience.com

[@smitakaramadi1071]

What happens when the input is current source?

[@Hey_sugar]

but in the last video you described that at t=0 Vr=I*R, Vc=0 as C has no charge and at t=infinity Vr=0,Vc=Q/C as I through resistor is 0.. i am confused now

[@mrthatcher8562]

Kinda late but for new people watching this video, there's an I (current) at infinity because there's a new branch for the current to go through (ie the parallel resistor to the capacitor)

[@NeelSandellISAWESOME]

@@mrthatcher8562 Thanks, your response really helped me understand :)

[@guard1an500]

Love what ur doing

[@testchannel7747]

You say in the video that the last two branches are in parallell (the one with the Capacitors, and the one with the 20 Ohm resistor) Why are the first and seccond branch not in parallell? (The one with the battery, and the one with the Capacitors)? They look parallell to me, so I would mistakingly have said that the potential difference between X and Y is 6 V

[@stepbystepscience]

Yes, the battery and the capacitor branches are in parallel. But the potential difference across points X and Y is not 6 V because some of the potential from the battery is used by the 10 ohm resistor.

[@testchannel7747]

Thank you! :D

[@khumaranasibli7668]

Very very helpful 👌👍

[@stepbystepscience]

Thank you very very much for saying so.

[@NitinPatilEmbedded]

Nice explanation.... Keep it up

[@stepbystepscience]

Nitin Patil Thank you for the comment and thanks for watching!

[@johnparks6936]

Great video, really helped me a lot! Just had one question if you don't mind - why is Vxy 4V when it is also parallel to the battery which is 6 V?

[@stepbystepscience]

Because 2V of the battery's 6V are being used by the 10 Ohm resistor. Oder?

[@johnparks6936]

Makes sense, ty

[@rabihatut]

@@stepbystepscience after long time the current in the circuit drops to zero. As result the pd across the 10 ohms resistor drops also to zero which means at the end the 2 capacitors are sharing between themselves all the 6V of the battery.

[@stepbystepscience]

@@rabihatut Not quite....After a long time the current through the branch with the capacitors goes to zero, but there will still be current through the outer branch with the resistors (why not?).

[@hasanyahya9171]

This analysis is just valid for DC source (Battery) , is not it ? Thank Sir !

[@stepbystepscience]

it is.

[@amofaga20]

When calculating for volts across caps don't write down the pico and micro sign like i did reading off my calculator, just the V for volts, lol. Preciate the tutorial.

[@skyemu8769]

Awesome!

[@mustafafall6715]

Good job. Nice videos.

[@charleslowkes3843]

You Sir are a god.

[@stepbystepscience]

thanks for positive comment