1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How do I find the emf and internal resistor of this cell of this circuit?

  1. Jul 2, 2012 #1
    This is a potentiometer circuit. I don't have the diagram so I hope you can follow me. This is the main circuit with the unknown emf E with internal resistance r of the main cell and with two resistors P and Q connected in series at the bottom of this rectangular circuit, p being connected near end a and Q near end b of the bottom of the main circuit. Another circuit is connected to the main circuit at end a and to c in between the two resistors P and Q. This circuit has a cell E1 of emf 1V, a resistor S and a galvanometer G.




    This is the question.
    When P is 20Ω it is found that the deflection of g is zero for Q when it is 17Ω. When P is 40Ω, again it was found that the deflection of G is zero for Q when it is 35Ω. Find the emf E and the internal resistance r of the cell.


    I tried finding the current through P and then finding the voltage through Q in both instances. I assumed the difference in the total voltages in both instances to be the voltage through internal resistance r. Am i correct? If not, how do I answer this question?
     
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted



Similar Discussions: How do I find the emf and internal resistor of this cell of this circuit?
Loading...