Internal Resistance of a Battery, EMF, Cell Terminal Voltage, Physics Problems
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- Опубликовано: 13 апр 2025
- This physics video tutorial explains how to calculate the internal resistance of a battery when connected to a load resistor. It explains the difference between the terminal voltage across the resistor and the emf or electromotive force generated by the cell. This video contains examples and practice problem showing how to calculate the terminal voltage and the battery and the internal resistance of the cell. The terminal voltage of a battery decreases when electric current is drawn from the cell. As the current delivered by the battery increases, the terminal voltage decreases.
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For nearly 2 years, this concept has baffled me. Now I totally understand. Big up
OH MY GOSH THANK YOU SO MUCH. NOW I FINALLY UNDERSTAND EVERYTHING THAT I MISSED IN CLASS. YOU EXPLAIN THINGS SO WELL TYSM FOR ALL YOUR VIDEOS AND PLEASE KEEP IT UP. THANKS.
OMFG U SAVED ME..ALTHOUGH UR VOICE ALWAYS MAKE ME SLEEP..U ARE A REALLY HELPFUL AND GOOD TEACHER..THANK YOU!
Thanks
@krisda there's this feature on the phone where you can turn up the volume
@@ericcartman1168 dude im on a MacBook Pro with headphones and all the volume options on max, I just have a ceiling fan on above me and I still barely can hear what he's saying.
excellent video on this topic, this was the only part of AS physics i was wobbly on before tomorrows exam
I fucked up my first paper 😭🔫
@@kyliek.9481 F
My exam is in like 30 mins 💀💀
Zeyin Mukhanov I ended up getting an A 😂😂
GG
Fr😂
Lmao feelz
i have my exam in 11hours :(
i loooveeee physics yayyy i loveee staying up to study because im too anxious to sleep
Eventhough I dont take any physic class , but I'm gonna save these video so I can learn it myself this summer time
That's awesome 🎉
thu ha ada
Very good
You are killin it with this videos. Do you have plans to start magnetic fields anytime soon?
Thank you so much. It's really helpful. You are a very good teacher...
Best explanation on this subject on RUclips. Thanks much.
At 3:10 you used the total resistance to solve for the current but at 8:42 you solved for the current by only using the R of the load resistor should it not be the total (r + R) when solving for the current ?
Yeah that part confused me too
At 3:10, ε is the voltage between the terminals of the entire circuit. In between those two terminals are both the resistive load (R) and the internal resistance of the battery (r).
At 8:42, the voltage being used is the voltage across the resistor alone. In the real world, this would be like using a meter to measure the voltage across a resistor.Therefore, you would only use the resistance of that element and the voltage of just that element to find the current through just that element.
The goal was to find the current. Because we didn't know the internal resistance, we couldn't use ε / (R + r) like we did before. Since both resistances are in series in this example, it makes it easy to find the current of the entire circuit because the current through R = the current through r = the current of the entire circuit.
This can be helpful but its more like an ASMR to me perfect vid to sleep in
Lmfao
My final first year exam in about three hours...
Wish me luck
I really enjoy your subject only when you add more questions to it
Such good video. Although it is not very logic, it is great for me to review.
This video cleared up a lot of things, thank you so much
8 years later I’m watching this video 30 minutes before my test😭🙏
Ur amazing sir, all your videos r very helpfull
V. clear explanation and logical working. Thank you
Does it really work in "real life"? I mean calculating internal battery resistance 12V car battery the way done in the video?
Who else is here in 2020 cause they skipped all their online classes?😂😭
I was sick for like 3 days and missed so much this man saved me
lmao me
I ended up falling.. turns out the pass rate of the course was 34% so at least im not alone...
shut up you burglAR
2021 and yes
Great vid .At the time 3:35 Why do we not multiply by 101 ohms being the total resistance?? Instead you multiplied by the 100 ohms resistor . I may have complicated this by asking plz explain...
If I understand your question right, the R=1ohm
R=100 ohm
Is more like part (i) part (ii)
The question can be taken as find internal resistance when external resistance is (a) 1ohm (b) 100 ohm
I have a question it actually comes from the text book titled "success in electronics" 2nd edition In Unit 2 Direct Current subtitle 2.14 problems. No 14 the last problem. It has fig 2.20, and the question says in fig 2.20, V is a high resistance voltmeter.
a) it reads 6V when the switch is open and 4.8V when it is closed. Calculate the e.m.f and internal resistance of the battery battery. Please help.
finally somebody that knows what they're talking about, excellent job, i can't believe the other ah's on youtube that are providing so much misinfo., it is ridiculous.
how we can calculate it from the graph though ?
Excellent explanation ...I really enjoyed your lesson 🤩🤩 am just looking forward for more lessons ☺️☺️
I can't speak english but, These lessons are so good.
This helped a ton- thanks man
my physics exam tmr :p
Nah physics is actually interesting when u understand it🎉
thnx a gazillion times !!!
Waw clean explaination. Thanks
2. Terminal pd across the battery is measured at 6.2 V. The battery consists of 2 cells
connected in parallel. Given that R_total is 3.1Ω and A measures 2 A:
2.1 Determine the emf of the battery.
How can I solve this JG?🤔
I am watching this video in my exam 😊 .
My exam is tommorow and I never studied physics from the beggining of the year💀💀
you great keep it up!
how to find emf when no current flows?
Thank you so much! it helped me a lot
Very good explanation .
Is total resistance same as effective resistance?
My brain is exploding trying to understand this stuff
What do we do if they didnt give us the internal resistence? Thanks tho
I really appreciate this🙏
On which app you teach us tell me plz?
Thank you 🥺
I have a question: if I were to find the internal resistance of a battery, should I use a resistor with higher resistance or one with a lower resistance? Thank you.
Did you find the answer yet?
you are a very good teacher thanks a lot sir
Hi, will you do a video on a VI graph and calculating the internal resistance + current + emf by using the graph please?
Thanks! And what if it's an old battery? What happens to the e.m.f. and the internal resistance as the battery ages and loses its charge?
First the e.m.f is what is written on battery's by company's and nothing happens to it but
The terminal potential is the actual value of the battery and as time gose it decrease bec of internal resistance of the battery and this is called lost potential
Then emf= t.p + l.p
Gud explanation
Can you do the same, but a little more practical? In this situation you wanted to calculate and measure internal resistance, and you had the Emf value. But in a real situation you cant relay on the value you get from the producers. Since most batteries wear out with use (at the same time internal resistance increases)
In other words. Calculate Internal resistance with Emf as an unknown value.
Agree
Agree ......please to do so
Thats a bold statment for someone with anime profile pic
@@fabijanskrobar1750 dead body reported
Explained well
Aren't they in parallel? You said series?
its series bro
@@oniyous2619 yeah I saw that after I commented bro 🧍
It is very helpful！
Thank you God bless you
Usefull demo. What software are you using here?
I talk about in this video: ruclips.net/video/rBSuMooMYrs/видео.html
I like how that guy uses a calc for multiplying 0.11988 and 100
How to find internal resistance given voltage, current and resistance? Electromotive force is not given
how do i calculate terminal voltage when internal resistance (r) is unknown? :"(
Get your voltage difference between your load. With that voltage find the current using ohm's law assuming you know the resistance of the circuit. After you have the current of the circuit and the voltage difference use equation: vr( the voltage difference you measured) = ( the internal resistance of the battery which you don't know)- Current multiplied by the resistance.
You simply get vr to the other side of the = sign to become a -vr and the internal resistance to the other side so the equation would be your internal resistance= - vr - ir. Vr is voltage difference and ir is current multiply by resistance that would give internal voltage.
Final touches 😊 exams at 2
Why during charging V= e.m.f + Ir??
Yes ! I'm not the only one that noticed
I have an assignment i should submit in less than 3 hours from now, And i have 100 problems to solve untill then
Two resistor 12 ohm and 6 ohm are connected in parallel and this combination connected in series with 6.25 ohm and battery has internal resistance of 0.25 ohm how to find emf of battery???
Do you not have the current given? Or the total power dissipated? If so, is it an expression you have to fond or a value?
Thanks a bunch🤩
A circuit consists of a variable resistor R connected in series with an ammeter and a cell. A voltmeter is connected in parallel across the variable resistor R. the cell is of e.m.f E and internal resistance r. For a certain value of R, the voltmeter reads 4V and the ammeter reads 1A. When R is adjusted, the voltmeter reads 2V and the ammeter reads 2.5A. Draw the circuit diagram and calculate the values of E and r. Please help!!
sir i love ur videos they helped me alot .sir if u have avideo which shows potential difference between two points in the circuit
Here it is:
ruclips.net/video/MnpJocNB6mc/видео.html
For your last equation you divided by -12 and your overall result was .42 however to my understanding another way I tried which goes by the rules of transposition if you have 11.9=12-0.238r if you move the r to the other side of the = side and the same with the 11.9 makes it -r=12-0.238-11.9 then change all the signs of positive to negative to both sides making it r=-12+0.238+11.9 and get result of 0.138. either I'm wrong or you are. If there is anyone here who understands this better then me please explain. Thanks
dayum, 11.9 = 12 - 0.238r ; here 'r' is multiplied to -0.238, so you can't just simply take only the 'r' to the other side of the equation, you gotta take the whole -0.238r to the left, if you want to, and the equation will be
11.9 + 0.238r = 12, then you can carry out this...
yea a magnetic fields video would be great
my exam is in 12 hours and im 12 weeks behind 💀
I'm writing a test tomorrow ☠☠☠🤧 it's on circuits and electrostatic
tysm i got it 4jan2022 7:28 pm
The book is by Tom Duncan. Reprinted 2013.
I've got a test in 7 hours 😭
I have exams in 39 minutes 😢
so how it went?
Exams in 30 min😭
Someone help i still don't understand 😢
Why 😭
you can also calculate internal resistance without finding current just by doing (1 - 11.9/12) x 50
What's the principle you're using?
EP1C (ocn) where did you find that? :\
Nicely explained
Thanks boss
or for last r=e-v/I same thing just easier for me to solve straight away if remember this
God Bless you
wow thank you
Are u ever going to do a face reveal
life saver
isn't that parallel?
🙏 thanks
thank uuu soo mucchh👍👍
Thanks a lot!!!!!
tysm
exams in an hour
Anyone studying this in 10th grade?
Me
I LOV EYOU
Abeg hu come from 2024😅
Hands down.
ادعم الفديو ترجم الى العربي ارجوك
what are you saying ???
He is proposing to include Arabic captions for the video
Use the question I gave you plz
🙏🏼
Anyone here from jnb😂
There isn't anything that you don't know.
Why your voice make me sleep🙄🙄🙄