EMF, Internal Resistance, and Terminal Voltage of Batteries Worked Example | Doc Physics

We'll do three quick NJCTL.org problems on terminal resistance.

[sailishmanandhar]

I, ve never had so much fun watching tutorial videos.thanks a bunch :D

[dogeeatsveggies]

when i watch his videos especially with problems like this one..i pause, solve the problem and check if i got it right.. at the last part i was like.. "yessss its 4.91 V!" and then he says screw it do it yourself ahahahahaha
hes the best youtube physics teacher, and i have Mr. partrickJmT for calculus..
you guys make the world a better place @____@ <3 <3

[ThutoMphoso-pbpi]

you're soo fun to watch, you make physics easy

[cl]

This is not the video I was looking for. I was looking for something a little more advanced...BUT I stayed and watched the entire thing because LOL! This is gold. I subscribed and I'm sure I'm about to find what I'm looking for

[nicholeewy]

finally!!! this saves me from failing my physics finals for tmr!

[remiecarreon]

informative and not boring!! 😁😁 the best!!

[victordolman]

You are amazing, finding fun in this sort of problems. A guy from NJ! I love it.

I'm lazy, and I recommend this lifestyle to everyone, especially in physics. I don't like to think too much. A little is fine, but when it can be avoided I'd rather do that. You start the first problem at 1:24 by writing down
V_t = V_emf - I R_int.
And then you insist that we think again, and use another equation, describing how V_emf works on the 'equivalent resistance'. Nah. Just use the first eq. and note that V_t works on the external resistance: V_t = I R_ext. Put in, rearrange, result. No thought.

When I think about it (which I shouldn't): do we need this whole 'equivalent resistance' concept at all? Instead of teaching it, we could have more 'guy from NJ' jokes.

[ernestgabrielcruz]

Thanks Doc Schuster! This is really helpful when i'm answering my homework. :D

[DocSchuster]

Victor Dolman Lazy and brilliant is one possible (and enviable) path to success in physics.  I like your solution.  However, I'm not sure it's less thinking.  Is it?  You're plugging one wonderful equation into a more esoteric equation, but I chopped the fancy framework off the problem and exposed it as a very simple one.  I accuse YOU of thinking more.

[YaseminTheBest]

This was too funny, thanks for the vid :')

[psalmdavid]

Hi can you pls answer this? A cell has a terminal voltage of 50.0 V for a current of 10.0 A, and 54 V for a current of 6.0 A. Find the electromotive force and internal resistance of the cell.

[bsdiceman]

lol What is terminal voltage vs V emf? I am wondering if the ratio between internal resistance and load resistance determines the voltage.

[edwardfayez]

the answer the follwing qustion when circuit is open the terminal voltage of a battery is 2 v, but this falls to 1.92 v .when the resistance of 0.12 ohm is connected across its terminals

[Breslinmusic]

In reference to the circuits you've drawn in the video, I have the following question: Given that the internal resistance is not an actual resistor per say, should the internal resistance not be calculated as though it were in parallel with the external resistance? Helpful video BTW, Thank you.

[LiegerZ]

Why can't I have you for Physics?!

[rbkatz]

You're like, 10 kinds of wonderful. Someone needs to send you cupcakes.

[dwarakesh]

No screw it do it yourself. Bye. Oh man this kind of attitude i actually like it so much. Kinda asking us to watch your videos by not telling it for me.SUBSCRIBED.-_-

[jakeentwistle]

Hello, I'm working a very similar question here in the UK where i first need to find the current in the circuit then the terminal voltage of the battery. I have two resistors in parallel so must use Rt^-1 = Ra^-1+Rb^-1 to get the total circuit resistance i need to add the internal resistance of the battery as Rc + Rt (this is how i get to the given answer)? I just wondered why you don't add the internal resistance as a parallel resistance to e.g(Rt^-1 = Ra^-1+Rb^-1+Rc^-1). Thats probably a silly question but when you draw the circuit the battery sure looks in parallel? Cheers

[vivekparmar]

what we do if we dont have a value of V and internal resistance, ?

[daman]

where do you live? I will find you I will have you as my physics teacher