Internal resistance proportional to current?

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SUMMARY

The discussion centers on the relationship between terminal voltage, current, and internal resistance in electrical circuits. As current increases, the terminal potential difference (pd) decreases due to the voltage drop across the internal resistance of the cell. The internal resistance is typically constant, meaning that for every ampere of current, a proportional voltage drop occurs, exemplified by a 1 Ohm internal resistance resulting in a 1 Volt drop per ampere. This relationship is crucial for understanding how internal resistance affects overall circuit performance.

PREREQUISITES
  • Understanding of terminal voltage and current in electrical circuits
  • Familiarity with Ohm's Law and its application
  • Knowledge of internal resistance in batteries and cells
  • Basic graph interpretation skills for voltage-current relationships
NEXT STEPS
  • Research the concept of internal resistance in various types of batteries
  • Learn about the impact of internal resistance on battery efficiency and performance
  • Explore advanced circuit analysis techniques using Kirchhoff's laws
  • Study the effects of temperature on internal resistance in electrical components
USEFUL FOR

Electrical engineers, physics students, and anyone involved in circuit design or analysis will benefit from this discussion, particularly those interested in the effects of internal resistance on circuit behavior.

CAH
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The terminal voltage and current are measured as the resistance is decresed through a cell with emf and internal resistance. Graph of V (y axis) I (x axis) shows straight line decreasing gradient.
1. Explain why terminal pd decreases as the current increases.

is terminal pd the same as pd/voltage? I thought the pd across a resistor would always be the same provided your not adding resistors. However the mark scheme says:

mention of pd across internal resistance or loss in internal resistance or emf>V,
pd across internal resistance/loss volts increases with current or correct use of equation to demonstrate

So does the internal resistance increase with the current and so voltage is lost through wires?

Thanks :smile:
 
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No. As with all resistances, the voltage dropped across it is proportional to the current and the internal resistance is usually assumed to be constant. That is a bit of an oversimplification for many components, though.
 
so the voltage will continuously drop to internal resistance? It seems like a lot of volts lost just to internal resistance?
 
CAH said:
so the voltage will continuously drop to internal resistance? It seems like a lot of volts lost just to internal resistance?
IF the internal resistance is 1 Ohm then every Amp will cause a drop of 1 Volt. There's no surprise there.
 

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