Batteries and Internal resistance

[sabak22]

A 6.0 V battery has an internal resistance r. The measured voltage (emf of the battery) is 6.0 V. When connected to a resistor R the terminal voltage is 5.9 V and the current is 0.18 A.
I managed to get a) What is the internal resistance r of the battery?
0.556 ohm

as well as b) What is the value of the external resistor R?
32.78 ohm

but i can't figure out what to do when they ask me
c) What is the energy dissipated inside the battery in 4.4 minutes?

and d)When a second identical battery is added in series and the external resistor is R = 29 Ohms what is the resulting current?

Please help me. I have been trying this for an hour!

 

[issacnewton]

c) Power dissipated inside the battery would be

I^2r

where r is the internal resistance. once you get power, find the energy consumed inside the battery...

for part d) , set up Kirchhoff's equation again...

 

[sabak22]

Thank you very much isaacNewton. But I am not quite sure how to solve the d part. Could you please expand a little bit? I am having trouble setting up the second identical battery in the circut.

 

[issacnewton]

have you learned how to use Kirchhoff's rule ?

 

[sabak22]

umm all we've learned this week was that Iin=Iout. Is that supposed to help me? I don't know what to with it.

 

[issacnewton]

http://academicearth.org/lectures/basic-circuit-analysis-method-kvl-and-kcl-mmethod

 

[issacnewton]

http://en.wikipedia.org/wiki/Kirchhoff's_circuit_laws

well there are two rules of Kirchhoff. the one you stated is Kirchhoff's current law.
what we need for solving current in the second case is Kirchhoff's voltage law.

 

[issacnewton]

here are some links to help you learn the Voltage Law

http://www.facstaff.bucknell.edu/mastascu/eLessonsHTML/Basic/Basic5Kv.html
http://www.physics.uoguelph.ca/tutorials/ohm/Q.ohm.KVL.html
http://www.wisc-online.com/objects/ViewObject.aspx?ID=DCE3002
http://www.youtube.com/watch?v=ByvywQ92fdw&noredirect=1

 

[issacnewton]

you should get some understanding of the voltage law to solve the problem

 

[sabak22]

just a quick question. will the two internal resistances be the same now that another identical battery has beenhadded? If yes then will the r= 0.556 like it was in the first case?

 

[issacnewton]

yes, the internal resistance is the same... its the property of the battery...
but now you have two similar batteries in series...

Edit: which book your teacher is following ?

 

[sabak22]

so what I am getting is something like this :

6-0.556-32.78i1-6-0,556-29i2 = 0

Does this make any sense? if not can you please boost me with a little help.

 

[issacnewton]

see, the batteries and the external resistor are in SERIES, so there is only one current throughout.

 

[issacnewton]

draw a circuit to help you

 

[Redbelly98]

Moderator's note: thread moved to Homework & Coursework Questions.