Thank you soooo much! I was close to crying from not understanding the book that I have read a LOT of times!! You're my hero!
@ItsRubenMorris5 жыл бұрын
fidel santos I’m past “close” at the moment. I hope this guy helps me
@HannahCaeru10 жыл бұрын
My unit 1 exam's tomorrow...all I can do is say thank you for all these videos, they're what has taught me almost all of AS physics. Thanks!
@DrPhysicsA10 жыл бұрын
Thanks. I hope the exam goes/went well.
@ahmedeloufir3 жыл бұрын
I am a 38 year old software engineer who is supposed to know all this, yet I sleep every night watching your videos. I discovered your channel less a year ago and it has been my favourite one since then... yet, you haven't posted any new one for quite some years and still your demonstrations need more deepening. But if you ever decide to do so, please don't change the humanity of your pedagogy, talking and writing and filming in the same manner. Thank you thousands times and more !
@yacinehannane29089 жыл бұрын
"There is resistance in the battery itself" Batteryception DUUUN DUUUUUUUUUUN
@lenakyony8 жыл бұрын
I feel like science would've been fun with you there
@yacinehannane29088 жыл бұрын
+Lena Kyony XD Thank you!!
@swervo30653 жыл бұрын
nerd
@josefinej39218 жыл бұрын
Thank you so much, this was the exact video I needed, you have no idea... I've been struggling to understand the idea of EMF and internal resistance for too long, and as "simple as it should be", I felt no one could give me a "simple" explanation. I believe my Physics book's description is far too inadequate, not to say confusing. This completely turned my level of understanding and I now finally think I understand this. This is primarily because you, in your explanations, leave few question marks to be left over as you more or less explain everything and in simple terms, I believe. So thank you :-)
@kamalthapa78607 жыл бұрын
These classes are really useful. Thank you very much.
@rahuldas-uv9eh8 жыл бұрын
the video was literally good and cleared all the doubt which i had in my mind regarding internal resistance..... thnxx alot☺☺
@zawaideh619 жыл бұрын
Thank you so much for those amazing videos I'm currently doing AS and I'm doing really well with your help.
@denispoutchninecosta48868 жыл бұрын
It's just what I was searching for Thanks
@MrZubair70810 жыл бұрын
Thanks! This really helped me understand this section that i was having trouble with.
@simranjoharle42206 жыл бұрын
This is one of the best explainations I have ever come across..... thank you Sir!... this really helped.
@TheFrazerboy9 жыл бұрын
great video your better then my physics teacher
@jdnandi66179 жыл бұрын
Than* You may want some help from your english teacher.
@JamDaaMan9 жыл бұрын
pikachu sucks I could say the same for you, your grammar is defective.
@JamDaaMan9 жыл бұрын
pikachu sucks Except that you put words straight after commas. Flawless is one word.
@JamDaaMan9 жыл бұрын
pikachu sucks At least I can retain some maturity as opposed to resorting to vulgar language. I guess it reflects your intelligence in a way - your limited vocabulary. Your grammar is terrible. Its is incorrect to leave spacing after commas. So don't lecture everybody else when you yourself can barley string a sentence together.
@arocks12345679 жыл бұрын
pikachu sucks u wrote "you didn't noticed a simple mistake", that's a grammar mistake not spacing -_-but u are right, people should look at themselves first! :)
@Zipo21410 жыл бұрын
Its awesome because I have an exam over resistance tomorrow! Perfect timing. Thanks!
@frango83525 жыл бұрын
Fantastic video. Absolutely worth the 20 minutes.
@AmineChM219 жыл бұрын
this is just beautiful
@duaaaq419310 жыл бұрын
this video is just great (: Thank you so much Dr PhysicsA
@deeptavker351510 жыл бұрын
Very helpful videos sir..:) nicely explained. Admire your work.
@gertwallenАй бұрын
0:48 Dr.Physics, someone told me that the classical concept of "electrons flowing in a circuit" is not correct but rather it's an electromagnetic wave (radiation) that travels in the circuit and not the electrons. Is this correct?
@fatimazohra222410 жыл бұрын
i had a hard time with internal resistance, but now i finally get it ! thank you !
@jeanpierredaviau74788 жыл бұрын
Is not the resistor kind of diluted in the mass of the battery? The électrolitic or chimical? So the internal resistor is in between the two poles. That would put the variable resistor in PARALLEL with the internal resistor intead of in series.
@angelachu83597 жыл бұрын
thank you so much. your video is so awesome, and I finally understand the idea of internal resistance.
@tchtmm3112 Жыл бұрын
I have a question and I want from you to answer it please: what is the diference between the efficative voltage and the Emf
@mtalhashahzad8999 жыл бұрын
when we open the switch then current should flow through battery and thus internal resistance will be offered and then the terminal voltage us not equal to emf
@serpentineflame5 жыл бұрын
The last time I heard conundrum it was because the whole saw I was using for cutting in the coach light outlets had a bent pilot bit, and my project manager lost his damn mind.
@clementl68438 жыл бұрын
Did you or can you make a video about the Norton & Thevenin models ? Thank you :)
@physicsSriLanka10 жыл бұрын
Thanks sir, we are from Sri Lanka, can you do this videos on 1080p full HD quality. they're really helpful. your voice is very clear to listening us than other teachers. Good luck
@ali-bb7so8 жыл бұрын
Very good video indeed
@claraj65219 жыл бұрын
How is that V= E - ( I * r ) ???? (15:46) Is it correct for Voltage across the battery =( E - Voltage across the external resistance or main resistance ). So it will be that V= E - (I * R ). There is no current, If Switch is open. So, Voltage across the main resistance is zero. Therefore, V = E - 0 => V = E.
@titan80847 жыл бұрын
small r = internal resistance
@AhmadKhan-sp3qb5 жыл бұрын
at 18:30, if there is only a single resistor in a circuit, wont it take all of the voltage of the battery? so if we change the resistance, in any case it will use all of the emf of the battery thus the voltage remains constant? further, if we increase the resistance, the current will decrease so why wont the voltage remain constant? where am i going terribly wrong
@drspinz9559 жыл бұрын
You cant plot that graph, because in order to get that ..SOMETHING should be a constant !!! which exactly is the constant?? R?? V?? I?? I don't get this help!!!
@silverchain55255 жыл бұрын
You are autistic. Go to 20:50. I don't care ur comment is 3 yrs old. Ur still autistic
@ModestMaker6 жыл бұрын
If I understand this correctly, this is why the measured bus voltage on my battery-powered circuit decreases as the current demand from adding loads increases. It's a function of that negative sloped V to I curve which is set by the internal resistance of the battery. So, if I have a battery with a large internal resistance, the voltage on the circuit decreases dramatically as I draw more current. Is that correct?
@Vulpes_Lagopus11510 жыл бұрын
Hi Dr. do you think you could do a short series of videos as an introduction to lie groups and lie algebras, at least SU(3) SU(2) U(1) because I think they are really important in physics and there isn't a lot of accessible material in an appropriate level, everything is very rigorous. They would also be complements of your video on rotation operators. I think it would be a great idea and would help a lot of people that in the future, like me, would like to become a physicist. Thanks :D
@johnlawrence567210 жыл бұрын
Yeah, I think that is a good idea because although I downloaded some books they are too specific. I just want to get some idea of it not to much but at least something.
@DrPhysicsA10 жыл бұрын
There is some basic introduction to these unitary matrices in my series on particle physics.
@Vulpes_Lagopus11510 жыл бұрын
DrPhysicsA Yes I know thats why i tell you, I saw your video and I thought it was a good idea for a sort of miniseries :D Also I thought you had finished your projects and you didn't know what to do next. By the way, do you have something in mind?
@legendfooty9 жыл бұрын
i don't get the graph for the variable resistor because as resistance increases current decreases so surely voltage stays constant due to v=ir not just v increases as r increases
@DrPhysicsA9 жыл бұрын
What time on the video does this occur?
@legendfooty9 жыл бұрын
17.5 mins
@legendfooty9 жыл бұрын
DrPhysicsA please reply
@ChristopheHerreman9 жыл бұрын
legendfooty The graph plots the voltage drop (over the resistor) against the current, not the battery voltage. When the resistor value increases, the voltage drop will be higher and the current will lower, and vice versa.
@legendfooty9 жыл бұрын
oh so its the emf that stays constant not the terminal pd due to v=E-ir and I increases V decreases
@fasanayorinde11943 жыл бұрын
I really enjoy the lesson
@williamjarrett979 жыл бұрын
Very good video, well explained. Thank you!
@jesuschal10 жыл бұрын
EXCELLENT PEDAGOGIC!!! I would wish all my teachers would have had your teaching skills. After watching this video I did my own test and I came up with a question. Let's say the my circuit has an intrinsic impedance. I would have three resistances in my circuit: the R (resistor on your explanation), r (internal battery resistor on your explanation) and Rc (impedance of the circuit without battery and without resistor R). How would I add Rc to the calculation?
@DrPhysicsA10 жыл бұрын
Since we are using a battery it will be DC. So any AC impedance effect would not arise and you would simply look at the resistive element of the reactance. you would simply treat that as another resistor.
@mStephanLouis8 жыл бұрын
You just saved my life
@so.meYeah7 жыл бұрын
best video on this subject ever!!!
@kimmidoll97176 жыл бұрын
This saved my life.
@larrybanks19617 жыл бұрын
"you should be able to draw this in your sleep" -Physics Don
@davidbellfilm10 жыл бұрын
At 15:00 you say that the current will be 0 and hence the emf will equal the voltage displayed on the voltmeter. Surely there will still be a current through the voltmeter?
@blink82355 жыл бұрын
Thank God for DrPhysicsA!
@MacyBoy1110 жыл бұрын
Fantastic summary! Thank you very much
@mahmoudm4517 жыл бұрын
I don't understand why when the circuit is close and you measure the voltage across the battery you get 4.5 V? shouldn't the battery and resistor work as potential dividers? it's like putting 1 ohm resistor beside a 5 ohm resistor, with a 5V battery, does that mean that when you measure the voltage of the 1 ohm resistor you will get 4.5? I'm puzzled.
@vishaljain49157 жыл бұрын
A voltmeter measures the difference in potential between the two terminals. If u look at the diagram, when the voltmeter is put across the battery, the right hand side terminal measures 0 V as all the energy the charges are carrying has been dropped across the resistor, as when charges come back to the battery they have no energy or in other words, all the energy charges carry is dropped across the circuit. So the right hand side terminal measures 0V. The left hand side terminal measures 4.5V as the charges gain 5v from the battery but lose 0.5V from the batteries internal resistance, so they leave the battery with a P.D of 4.5, this means the voltmeter measures 0 on the RHS and 4.5 on the LHS so the voltmeter reading is 4.5V
@augustsobolewski646 жыл бұрын
Probably a stupid question, but when "Voltage drop" is said is "Voltage output" meant.
@krisnegi26268 жыл бұрын
drPhysicsA to the rescue ......... great video !!!
@jackt42746 жыл бұрын
So does it mean that for an internal resistance of 0, the graph will plot a horizontal line, meaning no matter the current values you will always get the full voltage?
@davidsweeney11110 жыл бұрын
Hi, Im getting stuck on Karnaugh maps in my digital electronics, do you have any videos that can help me please? thanks.
@DrPhysicsA10 жыл бұрын
Sadly no. Sorry.
@deepakchandravanshi62747 жыл бұрын
powerful explanation...
@JackSteadlan10 жыл бұрын
very useful
@IvanKalamazoo5510 жыл бұрын
very good video before sleep... you've got such a relaxing voice!! thx for posting
@w1zzard4187 жыл бұрын
Very well explained sir!
@pervezjan307710 жыл бұрын
Hi! I am a fan of your vidoes and I use them in my classroom very often. Thanks for such a nice work Man! I do ask for some more help specially for Practical papers of Cambridge for AS and A level. (Physisc 33 and 52) If possible , up-load some examples papers which I can show to my students. Jan
@tomrp-yt24094 жыл бұрын
Hello DrPhysicsA, I am just curious whether this lecture still applies to yhe current ALevel Specification, because if so, it would be a great help to me! Thanks
@LifeOnHoth9 жыл бұрын
These videos are very nice. My question is no doubt gonna show that I have never had a physics class in my life, and I never did any good in math classes either :). However, I was (I like to say) born with an "unhealthy" interest in electronics. So my interest in that greatly helps me understand physics and math I never really got at school - and you teach it in a VERY good way - thanks :). Back to the question. When I watch the video, it is obvious to me that for the math to work out, assumptions need to be made, and based on that you get the basis for calculating this stuff. I'm just philosophizing here - couldn't there be an internal resistance in the voltmeter and ammeter to take into account too? And also other factors that would affect the results, like ambient temperature etc.? Hehe - I know it will seem obvious to those of you who are used to understanding math, physics and all that - that I might blend stuff together which doesn't belong - but if there is something to my philosophizing here - is it so that the math in the video above is really a simplified picture of what is really going on in the circuit, taking out certain elements to make it less complicated to understand...? Or am I just totally off? :) (it probably is so :p)
@Ovulationman979 жыл бұрын
There is a small amount in the voltmeter and ammeter but it is such a small value therefore we don't really need to take it an account. Same again with the temperature... I don't know if I'm right or not :)
@naimza19 жыл бұрын
Mourmour Man voltmeter has a vert very VERY high resistance rating. this is to prevent current flow in the voltmeter. this is also why it is connected in parallel. whereas ammeters have negligible resistance that is why it is connected in series.
@cooler36038 жыл бұрын
At 13:31 when i calculate i find voltage drop was 0.5. But when i measure it, will the voltmeter reading be 4.5 volt ? And also will the reading of voltmeter in the resistor be 4.5? Thanks!
@mrpeanutguy471910 жыл бұрын
Thanks a ton for these videos, they're really helpful. Would you ever consider doing an A-level maths series?
@DrPhysicsA10 жыл бұрын
Thanks your very kind comments. I have no plans to do the maths series.
@ZrxGR3Gx10 жыл бұрын
examsolutions does a level maths.
@m9u7shuriken7 жыл бұрын
12:45. It's called a 'parallel' voltmeter. Quantum Electricity guys!
@ReMoBoY9710 жыл бұрын
Thanks very much ! very useful video.
@MdSajir-bn6vb6 жыл бұрын
but shouldn't the gradient of the voltage current graph give the resistance of the object and not the internal resistance...?
@julienferte379510 жыл бұрын
Hello, I would like to know: what camera are you using? Are you using an external microphone?
@DrPhysicsA10 жыл бұрын
I use a Panasonic SDR SDR S26 and I switch off the autofocus. I use the internal microphone of the camera.
@julienferte379510 жыл бұрын
Thank you for these details, I am interested in creating similar teaching videos, in other fields of knowledge. How do you make the camera stand above the papersheet? A peculiar device or a handmade thing?
@DrPhysicsA10 жыл бұрын
Julien Ferté It's just a standard camera stand. I arranged for the Camera to point vertically down onto an A3 sheet of paper.
@anshumanmishra25557 жыл бұрын
Good
@roseroseey63813 жыл бұрын
Thank you so much, you really helped me
@anonymousrhino51218 жыл бұрын
But what does the area under the line give us?
@infuze66474 жыл бұрын
18:34 as the voltage increases the current decreases? Wait I’m confused, shouldn’t it be “as the voltage increases the current increases?”
@whiteguyplays62299 жыл бұрын
I don't get graph of E/V against 1/R to find r (internal resistance)???
@kurdman1234567810 жыл бұрын
Is this AS or A2 because im doing AS AQA unit 1
@MrAlbashiri8 жыл бұрын
Thank you very very very very very very very very much.
@viknesavetrivelan33529 жыл бұрын
why do they still maintain the fiction that current flow from postive terminal to negative terminal ?
@MathraMania9 жыл бұрын
Probably for the hassle of correcting every single book that's already been published. :/ The new books nowadays mentions clearly about this problem.
@RoyAlexander7 жыл бұрын
brilliant - thanks for this.
@babysuyash6 жыл бұрын
which potential drop is great is it of variable resistor or internal resistor ?
@faizmalik92105 жыл бұрын
It would be less confusing if the practical battery is drawn as box containing an emf in series with an internal resistance.
@mtj19997 жыл бұрын
Still can't understand why voltage drop across the battery equals to E.M.F minus voltage drop across "battery". If anyone has evidence then plzz do share
@naimza19 жыл бұрын
thank you this was very helpful
@skyleonidas92707 жыл бұрын
You are genious mannn how u know all diss?
@jimdogma153710 жыл бұрын
Dr. PhysicsA, can you do a video on the new BICEPT experimental results with the gravitational waves, what these results are, mean, and their implications? Thanks
@DrPhysicsA10 жыл бұрын
I'm not sure there's very much to say at the moment beyond what has already been promulgated.
@jimdogma153710 жыл бұрын
DrPhysicsA Thanks for replying. Actually PhysicistMichael's channel did a great report in the BICEP experiment I recommend everyone check out. I even gave your channel a plug there cause both your channels are cooool ;)
@TheEngraver10010 жыл бұрын
So basically, Electromotive force can be analogous to potential energy? If so, is it a force?
@DrPhysicsA10 жыл бұрын
No it is not a force. Even though it is called the force. As you say, it essentially is the potential energy stored in the battery. It is measured involves which is work done (or potential energy) per coulomb of charge moved.
@sahilpatel613810 жыл бұрын
Very Excellent video, thank you :) and do you use marijuana recreationally sir or have ever have experienced with it ? (Legitimate question)
@SorryCrane169 жыл бұрын
And where did that come from 😲🔫
@JohnSmith-cy8hq10 жыл бұрын
Hello, I did my exam yesterday and I'm pretty happy with how it went and I've got you to thank for that. Thanks, I really appreciate your videos. There was one question in the exam that kind of bothers me now. Besides the strong nuclear force, which force acts between protons in a nucleus and what is the exchange particle of this force? I wrote electrostatic and exchange particle virtual photon. Virtual photon is definitely correct but I'm not sure if I should've written electromagnetic force instead of electrostatic. What do you think? Thanks again
@DrPhysicsA10 жыл бұрын
Personally, I would give you the mark.
@faizasikandar60504 жыл бұрын
What do yoy mean by internal resistance. What thing is resistance
@PeterWalkerHP16c4 жыл бұрын
A battery is not an ideal current source. If you have a perfect conducting wire and short the battery out, the actual current will be less than the ideal current because the battery has some resistance internally.
@tatevarevikyan68528 жыл бұрын
God bless you
@mohammadaniyal7 жыл бұрын
awesome thanks :D
@MrPowellfactor10 жыл бұрын
I thought electrons exchange photons this was electrical charge , why do I keep hearing people talking about the flow of electrons?
@ahmedal-ebrashy36916 жыл бұрын
Why I has a large value when V is 0? I thought no voltage no current!
@maviosmachethe1447 жыл бұрын
i get it now thanks
@harrisonrossiter56084 жыл бұрын
you a goat
@aryagupta36496 жыл бұрын
Electricity flows because the - side of the battery has MORE NUMBER OF ELECTRONS than the + side of the battery which has LESS ELECTRONS. It is totally wrong to say that charges attract, so electrons move from - to +. Here, + & - are not charges, they simply denote that - means more number of electrons = higher potential while + means less number of electrons meaning lower potential. Thus electrons move from higher potential to lower potential i.e, from - to +. By convention, we say that current flows opposite to the direction of flow of electrons, i.e from + to -. Guys this is a very important concept. Although f*cking lazy, seeing such crap being posted in a video and it being on the internet where thousands of unknowing people will learn from it. And if you feel like I'm wrong, think logically. If unlike attract, if there even WERE unlike charges in place of the + & -, wouldn't the attraction have been equal for BOTH resulting in an attraction from both the sides resulting in the +ve & charges meeting ? Instead of a one-sided flow of CURRENT ? ;))
@mohammadaniyal7 жыл бұрын
17:46 one question. can the voltage go zero if the value of the current reaches some particular value because the graph you made indicates so as the gradient is touching the axis
@DrPhysicsA7 жыл бұрын
No. The voltmeter operates by having a very high resistance and so a very tiny amount of the current flows thro the voltmeter. Most of the current flows through the resistance. But if the resistance value becomes too high (and higher than that of the voltmeter), then most of the current will flow thro the voltmeter and the experiment ceases to be valid.
@mohammadaniyal7 жыл бұрын
DrPhysicsA i understand thank you
@itstwinklerkate7 жыл бұрын
i am too distracted to listen because his accent makes me feel like im in Hogwarts lol
@sahilthakur13227 жыл бұрын
sir what is internal resistance
@rithvikshindihatti12157 жыл бұрын
I think the circuit is not in series.:(
@harrisonrossiter56084 жыл бұрын
gg this helped thank you
@gretawilliams87997 жыл бұрын
+drphysics A. Pls clarify this solution for me. physics-ref.blogspot.com/2015/08/physics-9702-doubts-help-page-187.html question no 913. ... iv) 2 and 3 I thought this in two ways, and it would contradict the other answer through either one of them. ... 1) Pd is the amount of voltage a component can take, with this... T pd across A = 4.4+ Ir (which is wrong) and T pd across B= 2.3 +Ir (which is correct) 2) terminal pd across a component is the (total emf - pd of that component) which gets me the answer to 2 but 3 becomes wrong.. aagghhhh
@harshitkhanna19185 жыл бұрын
Won't the voltmeter provide potential drop
@PeterWalkerHP16c4 жыл бұрын
yes. Modern volt meters have a very high input impedance to reduce this effect. Older meters had a 'table' on the dial to allow you to calculate the effect of the meter on the circuit being measured.
@magn81955 жыл бұрын
18:49-18:50
@CudiTV.3058 жыл бұрын
The voltmeter doesn't have resistance ?
@mbikov8 жыл бұрын
+Rony Polisaintvil It does I recon. But very insignificant.
@titan80847 жыл бұрын
Serkan Demirel what the actual fuck is wrong with you " Ideally, an ammeter should have a zero resistance value, but materials with zero resistivity are not present" CAN YOU FUCKING READ???? i wasnt even talking to you
@imagination77106 жыл бұрын
Actually voltmeters have a massive resistance, so they don't take any current from the circuit
@TheCsePower9 жыл бұрын
Something is bugging me If im correct you said, V=Emf-Ir then at I=0, V = Emf but didnt you say earlier that V=IR? If that is true then why not Emf = 0R =0?
@DrPhysicsA9 жыл бұрын
emf is total voltage capability in battery/cell. V is the "external" voltage (i.e. the amount available after driving through the internal resistance)
@raykay1269 жыл бұрын
DrPhysicsA Isn't there current flowing around the circuit connected to the volt meter though?
@DrPhysicsA9 жыл бұрын
Ray Kay Yes but the voltmeter has a very high resistance so the current is extremely small.
@alimoazzam118 жыл бұрын
Sir, I have the same question as someone in the comments. When you are trying to measure the Internal resistance at 16:15 in the video, you put a variable resistor in the circuit and plot the voltage drop across it against the current. My question is, shouldn't the voltage remain constant? Since you increase the value of the resistance, current decreases correspondingly, so that V remains constant. Where am I muddling it up?
@kinshukdua8 жыл бұрын
are you talking about the Voltage in the Voltage Current graph around 17:13??? Then he is talking about the voltage *through the resistor after the voltage drop* so when you change the resistance R the the voltage *through the resistor after the voltage drop also changes, it's NOT the total voltage* and because the total resistance has changed the current also changed (because V = IR) I had the same confusion when I had first learned about it.
@mahmoudm4517 жыл бұрын
I get where you're confused. Think of the variable resistor as one resistor split into 2 parts by a sliding contact, one part is the one you use and you take an output voltage from it, and the other part you don't use it, but it acts as a potential divider with the other part. The voltage of the output you're using can be increased by increasing the length of the part of the resistor that you're using, by simply moving the sliding contact. Remember that the sum of the voltages of the 2 parts of the resistor is always equal to the voltage of the battery, so by increasing the voltage of one part, you're in turn decreasing the voltage on the other part. Now when you increase the resistance, you also increase the voltage, but the current drops...you may say that when the voltage increase, the current must also increase and that's true, but think of it in this way: when the voltage increase, you can't get extra electrons from outside to compensate for this increase in voltage and so the number of electrons in the circuit is limited, and thus the current is constant. Think of it as 2 horses pulling a cart across a rocky path (lets call it x), if the path is short (small resistance) then they will spend little energy crossing it (low voltage) and they will pass it very fast (high current) becuz although it's rocky, but it's very short. Now when you increase the length of the road( increase the resistance) you're inturn making it MORE ROCKY, and so the poor 2 horses will have to spend more energy (more voltage) to cross it, and since the path is more rocky, they will take longer time to cross the distance x they crossed that they crossed before and thus the current falls, since there are no other horses to come and help. hope that makes sense? I tried to make it as simple as possible.
@alimoazzam117 жыл бұрын
Mahmoud Matar thank you so much and also the previous commenter :) I had forgotten about my comment but maybe others can benefit from your kindness