How Do You Calculate the EMF of a Cell in a Circuit?

[DeanBH]

http://img.photobucket.com/albums/v345/crimsonflames/ddsa.jpg

thats the circuit.


isn't the equation emf = I(R+r)
0.032 * 900?

isn't right and i know it isn't, so i don't know what to do! =(

 

[Hootenanny]

http://img.photobucket.com/albums/v345/crimsonflames/ddsa.jpg

thats the circuit.


isn't the equation emf = I(R+r)
0.032 * 900?

isn't right and i know it isn't, so i don't know what to do! =(

HINT: You need to apply Kirchoff's rules here.

 

[DeanBH]

I know I need to find the difference of of the volts about the 2 resistors.

it ends up being 1 volt, but how the hell does i(R+r)=emf come into that

 

[Hootenanny]

I know I need to find the difference of of the volts about the 2 resistors.

it ends up being 1 volt, but how the hell does i(R+r)=emf come into that

That equation is valid only for two resistors in series, i.e. where a cell has an internal resistance r and is connected to a load resistance R.

As I said previously, you need to apply Kirchoff's laws here.

 

[DeanBH]

I did, the answer is 1

just doesn't make sense.

 

[Hootenanny]

I did, the answer is 1

just doesn't make sense.

I also have emf = 1V. So what doesn't make sense?

 

[DeanBH]

Why do i have to count one of those volt readings as negative, and why inst it 1/r it looks like a a parallel

 

[Hootenanny]

Why do i have to count one of those volt readings as negative, and why inst it 1/r it looks like a a parallel

What is Kirchoff's voltage/loop law?

 

[DeanBH]

What is Kirchoff's voltage/loop law?

no idea

 

[Hootenanny]

As I said previously, you need to apply Kirchoff's laws here.

I did, the answer is 1

What is Kirchoff's voltage/loop law?

no idea

How can you apply Kirchoff's voltage law if you don't know what it is?

 

[DeanBH]

guessed, that the volts in the battery would have to make up for the difference. but why is the amps 0.06 out of 0.032, if the volts were 5.2 instead of 4.2 in the right part of the circuit it wouldn't fit the rule RI=v