- #31
AdityaDev
- 527
- 33
That is what we want. Now the potential difference across the resistors will be different.Faris Shajahan said:
Measuring resistance using potentiometer
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SUMMARY
The discussion centers on measuring resistance using a potentiometer, specifically addressing the relationship between current and potential difference across resistors R and X. Participants clarify that while the current through the potentiometer wire remains constant, the potential differences across R and X vary due to their differing resistances. The balancing lengths, l1 and l2, are directly proportional to the potential differences, leading to the conclusion that the current and voltage differ in each case, contradicting some textbook assertions. The importance of considering internal resistance in calculations is emphasized, as it affects the terminal voltage and overall measurements.
PREREQUISITES- Understanding of Ohm's Law (V=IR)
- Familiarity with potentiometer theory and its applications
- Knowledge of internal resistance in electrical circuits
- Basic principles of Kirchhoff's laws
- Study the concept of internal resistance in circuits and its impact on measurements
- Learn about the practical applications of potentiometers in measuring voltage
- Explore the derivation and implications of the formula E = I(r + R)
- Investigate the role of rheostats in maintaining constant current in circuits
Students studying physics, particularly those focusing on electrical measurements, as well as educators seeking to clarify concepts related to potentiometers and resistance measurement techniques.
- #32
andrevdh
- 2,126
- 116
Usually this experiment is done with the resistors connected in series to the cell, in which case the
current will be the same through both resistors.
For this particular setup I can only reduce it to two unknowns, the resistance X, and the internal resistance of the cell.
current will be the same through both resistors.
For this particular setup I can only reduce it to two unknowns, the resistance X, and the internal resistance of the cell.
- #33
Faris Shajahan
- 29
- 4
AdityaDev said:
Yes, it will be different but still it would be impossible for us to calculate the value of ##X## as we don't have the value of ##r## given in the question.
Instead if they say there is a rheostat in series with ε in order to maintain constant current in both the cases, then we can calculate ##X## as
##X=R\frac{l_2}{l_1}##
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