Characterizing Voltage Sources: Finding V0 and r using a Variable Resistor

AI Thread Summary
In the discussion about characterizing voltage sources, participants clarify how to determine V0 and internal resistance (r) using a variable resistor connected to a battery. V0, or open circuit voltage, is identified as the voltage at the y-axis intercept when current is zero, which is crucial for accurate measurement. The internal resistance can be calculated using the short circuit current. Participants confirm that understanding the relationship between V0 and current is essential, as internal resistance prevents achieving zero current. Overall, the method discussed effectively characterizes the voltage source by analyzing the circuit's behavior at varying resistance.
mitsuruangel
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Homework Statement


A variable resistor, R, is connected to the terminals of a battery (dashed box in the diagram). The graph below shows data collected in the circuit as R is varied. What is V0, in volts?

What is the internal resistance, r, in ohms?

should the V0 be measured at the top of the line where it is at the smallest current? because that is what the TA explained to do, I tried and I can't seem to get it right
 

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Did you extend the line backwards to where I=0(where it cuts the y axis)
 
mitsuruangel said:

Homework Statement


A variable resistor, R, is connected to the terminals of a battery (dashed box in the diagram). The graph below shows data collected in the circuit as R is varied. What is V0, in volts?

What is the internal resistance, r, in ohms?

should the V0 be measured at the top of the line where it is at the smallest current? because that is what the TA explained to do, I tried and I can't seem to get it right

And adding one more question to Dadface's post, what is special about where it cuts the y axis?
 
that worked! thanks
 
mitsuruangel said:
that worked! thanks

But why did it work. Do you understand that part?
 
Because V0 should be at lowest current (ie when it is 0) but the internal resistance keeps it from actually getting there?
 
mitsuruangel said:
Because V0 should be at lowest current (ie when it is 0)

That part is correct. V0 is the "open circuit voltage", so when no current is flowing. The other thing you can use to figure out the internal resistance is the "short circuit current". Once you have V0 and Rs, you have characterized your voltage source.
 

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