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Finding the emf and internal resistance of a cell

  1. Dec 5, 2007 #1
    I hope someone can help me with my coursework by making sure my method is ok and is actually correct for my experiment. Note. I will not actually be doing this it is just a plan of what I could do!

    1. I am provided with a cell of approcimate EMF 1.5V, an approximate internal resistance of 1Ω and an approximate energy capacity of 1.5Ah. I have to plan an experiement to find the EMF and internal resistance.

    2. I know that i will be using the equation ε=Ir+IR and rearranging it to give V= -Ir +ε and linking it with the general equation for a linear graph y=mx+c. I know the y intercept will be the EMF and the gradient, -r, will be my internal resistance.

    3. For my method i will be setting up my experiment like this:http://img232.imageshack.us/img232/774/experimentma5.th.jpg [Broken]

    I want to know if my method is correct. I will turn on the cell and adjust the rehostat until i find the lowest current recorded on my ammeter. I will then read off my voltage and make a table of both readings. I will then adjust the rheostat each time so I take 10 readings of voltage and current but i will not exceed 1.5 amps. Does this method seem ok? I am confused on whether it is correct or not.

    Thanks in advance for your help,


    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Dec 7, 2007 #2

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    Seems pretty all right to me.
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