A Level Physics Revision: All of Capacitors (in under 21 minutes)

[@ItzAdz]

This is the third time I've come back to this video. I just want to heavily thank you for the easily accessible and comprehensible revision videos you make because they help sooo much more than any other videos on this platform. I'm in my second year and I struggle revising topics by myself due to the extent of information required to be learnt, but your topic videos make it seem short and simple, encouraging me to watch them and write notes. Your videos alone, including you overviewing topic specified exam questions, have gotten me high grades in multiple exams and I hope to achieve an A in my upcoming final A level exams. Once again, thanks a lot!!!!!

[@zhelyo_physics]

Wow!! Amazing, well done on the grades and your understandign of the subject! Honestly, comments such as these genuienly make my day! Good luck revising and drop me a comment if something doesn't make sense!

[@thomasparsons3166]

What did you end up getting and how did you revise

[@kskeedits]

Got exams in a month, watching all your videos on 2 times speed. You're a lifesaver sir.

[@zhelyo_physics]

Thanks for the comment! Good luck and let me know if something doesn't make sense!

[@yasminkhalifa8709]

Stupendous video!!!!!!!!!!!!! to be pragmatic you're fabulous, keep it physics teacher, you're doing an excellent job by helping A level student around the world, we need you in our current generation, I should recommend your channel one day, As an A2 level student your videos are helpful Masha Allah

[@zhelyo_physics]

Thanks a lot for the kind words! Good luck with revision!

[@zandermercury9308]

I missed this entire lesson when I got covid and I tried to learn it myself using the PowerPoints they sent us but this video is the only thing that made sense to me 😭😭

[@zhelyo_physics]

Glad to hear you managed to catch up and it makes sense! : )

[@PyroGhast-b6o]

Man, you can't know how much you've helped me. You are the flippin' GOAT of youtube's physics teachers. I wish you the best. THANKS

[@zhelyo_physics]

thank you so much for the amazing comment!! Very much appreciate it.

[@averageisekaifan]

tysm for making this chapter so digestible

[@zhelyo_physics]

anytime! Glad it makes sense! : )

[@raheemkhan2007]

Thanks alot for this video. Im new to A levels and the topics were haunting me. I couldn't understand much of capacitance from the book but after this video everything seemed to click. I also took detailed notes and shared with my classmates. A few of whom asked where I got them from (Our teacher didn't spend too much time covering this chapter, so I don't think anyone had a good grip on it). I recommended your channel to all of them. Once again, thanks alot :).

[@zhelyo_physics]

wow thank you so much for the kind words and the recommendations! Very much appreciated, comments such as these genuienly make my day!

[@prith7900]

Hey just started A2 levels and this is such a great resource. thank you so much for all your help

[@zhelyo_physics]

thank you so much for the comment! Very much appreciate it!

[@umarazam1182]

sir this is so good i cant thank you enough you are literally a legend

[@zhelyo_physics]

Anytime! Glad this is useful!

[@StickmanVenomCookie]

This made so much sense. Thanks!

[@zhelyo_physics]

anytime! thanks for the comment!

[@harrycole3941]

literal legend thanks man

[@zhelyo_physics]

anytime! thank you for the comment!

[@kashfiyaahsan7977]

14:27 "as we can see, no pun intended" 😭🤣

[@TDuncPiano]

In ALL parallel circuits is the voltage across each branch the same? 6:31

[@zhelyo_physics]

in most exam questions yes, otherwise we apply Kirchoff's 2nd law across a loop to find the p.d. Hope this helps!

[@flippergail9946]

Hi ZPhysics, this is a great video which I am using for my revision for mocks but I have just one thing I am confused about. At the end of the video you say that the current will decrease as the capacitor charges because the P.D accross the resistor is decreasing, but isn't the P.D across the capacitor increasing so maintaining the current?

[@zhelyo_physics]

Great question! So current is definitely decreasing since across the fixed resistor: V=IR, V decreases, R is fixed and therefore I must decrease. I hope this clears it.

[@theaerograndprix]

can you make a video going through capacitor questions please

[@zhelyo_physics]

There are already some within the topics of the capacitors playlist but more will be coming out.

[@eraldeshapriya2573]

this video is awesome thank you so much

[@zhelyo_physics]

Anytime!

[@osowayz]

thank u so much bro

[@zhelyo_physics]

Anytime, thanks for the comment!

[@HassanKhan-ss1yj]

Hello! Does this video cover every single thing about the chapter? Can I use it as the sole source to prepare the whole chapter? I missed a lot of classes at school.

[@zhelyo_physics]

I cover every point on the OCR Physics A specification, the syllabuses are very similar on different exam boards but you need to find your syllabus and check if there are any differences. As this covers only the theory side of it I recommend lots of past paper questions on the topic around it. Hope this helps!

[@thevinecompany7733]

Hi can you just explain why charge decreases when discharging? I can't seem to get my head around current charge and voltage changes during discharging and charging.

[@zhelyo_physics]

Sure, literally electrons go from the negative terminal in the direction of the positive, creating current. With fewer unbalanced electrons, the electric potential between the plates is lower and hence lower voltage. Hope this helps!

[@VLAD_BBX]

Amazing video, thank you

[@zhelyo_physics]

Thanks! Glad it is helpful!

[@nosir1479]

How about uses of capacitors? In the OCR A book, chapter 21.6, there is a topic on uses of capacitors. Im struggling to understand how a rectifier circuit works.

[@zhelyo_physics]

I can do a video about this type of circuit. Often in uses of capacitors you may be asked to state the use of a capacitor and something like a flash in a camera would score the mark. Or the capacitor problem may just be applied to a situation in a circuit. Hope this is helpful!

[@nosir1479]

@@zhelyo_physics Okay! I’d love to a see video on it just so I have a complete grasp of the topic. Your videos are amazing by the way, I think you’re extremely underrated.

[@zhelyo_physics]

thanks a lot! Much appreciated!

[@passionate_8068]

Great video! But just wondering if you have anything on dielectrics?

[@zhelyo_physics]

Thanks! Not specifically, but I have some on parallel plates capacitors if this helps! kzbin.info/www/bejne/fXjLpqOufKaIeLcsi=yzxUfTbHiWBXOsZw

[@flamexc]

At 18:07 why is Vr swapped for the equation instead of Vc? Shouldn't it be Vr + V0e^(-t/RC) instead?

[@flamexc]

Is it because the pd across the resistor is decreasing and the pd across the capacitor is increasing?

[@zhelyo_physics]

precisely right! at any time they need to add up to the emf by Kirchoff’s 2nd Law. Hope this helps!

[@aaronkibs8353]

18:16 why do we use Vc and not the exponential equation like we did for Vr

[@GabrielSzatan-g3b]

the exponential equation (like for Vr) is used for discharging only. the reason Vc is different is because we're finding Vc for when its being charged.

[@moeezf3344]

Is this playlist for entire A levels? Or are some chapters left?

[@zhelyo_physics]

Depends on the exam board, the entire course on most exam boards, AQA can have a couple of bits left which I will film soon. Always check with your syllabus.

[@binodtharu4910]

You didn’t cover how capacitor store energy and not charge. You also didn’t talk about parallel plate capacitors. Are they not in the OCR syallabus ?

[@zhelyo_physics]

Hi, in OCR this is done in Electric Fields as it's way easier to understand after you have done the electric field between two parallel plates. Covered here: kzbin.info/www/bejne/bYKucmaeZZmhhK8 Hope this helps! With regards to storing energy and not charge, which exam board do you do? I'd love to look at the syllabus. The net charge remains the same as the charge is always balanced by electrons leaving and entering the capacitor and stored within the electric fields of it. I should do a video about this, really interesting question.

[@binodtharu4910]

@@zhelyo_physics I do CIE board. I’m actually not from UK. I’m from Nepal. I am doing A levels from Nepal. Here there is no difference between the boards. All a level students in Nepal I guess study under the same board.

[@Freepalestinefromisnotreal111]

this may sound dumb,but in the series and parallel section, wasnt that talking about resistors? the same equation ie 1/c= 1/c1 etc... i learned about resistance

[@zhelyo_physics]

It's an excellent question! I actually made a whole video about this: kzbin.info/www/bejne/p5nPnXSkobR6qdE (by the way, the equations are similar but also reversed)

[@pathtopiety810]

Sir ,does CURRENT also Decreases while discharging of capacitor with time ??

[@zhelyo_physics]

yep! Highest the beginning of the discharge and then decreases exponentially.

[@uzairasim1851]

Hi, What is 'e' in expotential equation? Btw amazing explanation thoughout!

[@zhelyo_physics]

Thanks a lot for the comment! It's a mathematical constant, e, equal to around 2.718 etc, if you look at your scientific calculator you will find a "e^..." button that allows you to raise e to a specific power. Hope this helps!

[@uzairasim1851]

@@zhelyo_physics Thankssss appreciate your awesome helpp and contenttt!!! KEEP IT UPPP PLZZZ

[@johngomez6428]

Is there nothing on dielectrics as I have seen a few questions on them.

[@balajipalaniappan6804]

Is there a video on Dielectrics??

[@zhelyo_physics]

not a dedicated one, I do have one on parallel plate capacitors mentioned here: kzbin.info/www/bejne/bYKucmaeZZmhhK8 Which exam board are you doing? I can have a look at making one.

[@ninjadog5800]

Is this for aqa

[@zhelyo_physics]

All examboards, physics doesn't change. However check with your syllabus, there may be minor differences

[@ninjadog5800]

@@zhelyo_physics thanks

[@thegreatnumi]

What is e and it’s value in the Vo equation

[@zhelyo_physics]

this is the exponential constant, the base of the natural log. You don't need the value to solve the problem with most calculators you will see a button e that will automatically help you calculate. If you do need the value it's around 2.718

[@thevinecompany7733]

Also in the 2017 ocr exploring paper q21,b ii. How come you've used the discharging equation when you said it was charging?

[@zhelyo_physics]

I can check the question later but I think that question relates to the voltage across the resistor when charging. So the p.d. across the resistor decreases with time using the exponential equation.

[@studywithyan697]

9:26 why am I getting 1.137*10^12

[@studywithyan697]

never mind, I thought e is the elementary charge haha

[@rithikars]

lol

[@archiesutherland6127]

when multiple capacitors are being charged? Does the voltage of each one of the capacitors add up to V naught in series and would they all share the same charge?

[@zhelyo_physics]

They would all share the same charge that would increase according to the capacitor charging equation shown towards the end of the video.

[@archiesutherland6127]

@@zhelyo_physics and in parallel they can have different charge but same voltage?

[@zhelyo_physics]

@@archiesutherland6127 yep! precisely

[@callmeandrew9949]

Thanks bro

[@zhelyo_physics]

Anytime

[@jonathoncornly7779]

Do charge, voltage and current across the capacitor AND resistor exponentially decrease?

[@zhelyo_physics]

You mean when discharging? Depends on the circuit, however the p.d. decreases, the current decreases from an initial high value, across a resistor, p.d. will typically increase, due to Kirchoff's 1st Law. When charging - p.d. across the resistor decreases, p.d. across the capacitor increases.

[@jonathoncornly7779]

@@zhelyo_physics Thank you so much for your replies: I will never forget how much you've helped me get through this stressful time. I understand that voltage, current and charge across the capacitor decrease exponentially when discharging but what happens to V,I,Q of the resistor in series?

[@Solomon-ie9cz]

really helpful

[@zhelyo_physics]

Thanks a lot! Glad to hear!

[@jonathoncornly7779]

How do we know the voltage across capacitor increases when charging?

[@zhelyo_physics]

the charge on it increases, there is literally a built up of unbalanced electrons which creates a p.d.

[@yasasvimunasinghe1512]

hey is this for IAL physics ?

[@zhelyo_physics]

Hi yep! Well I followed the spec I teach OCR however 90% of the spec is the same, I would just check with your spec for minor differences.

[@liveszain]

Do you have a playlist for capacitance?

[@zhelyo_physics]

Yep! kzbin.info/aero/PLSygKZqfTjPAhARTJMkcRHhNS-O9UZxnh

[@HassanKhan-ss1yj]

@@zhelyo_physics Hey, why is there a separate playlist as well? Does this video not cover everything about the chapter?

[@juantw0]

The first question, I have no idea how you got that answer, can you help

[@zhelyo_physics]

Can you give me an exact time of the video?

[@juantw0]

@@zhelyo_physics 9:30, i put numbers into my calculator, with epislon nought value of 8.88*-12 and i still don't know how you got 3.29 volts.

[@zhelyo_physics]

@@juantw0 so e is not epsilon in this case but the exponential function, use the "e to the power of.." button on your calculator. Hope this helps!