Internal resistance proportional to current?

  • Thread starter CAH
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  • #1
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:
 

Answers and Replies

  • #2
sophiecentaur
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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.
 
  • #3
CAH
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so the voltage will continuously drop to internal resistance? It seems like a lot of volts lost just to internal resistance?
 
  • #4
sophiecentaur
Science Advisor
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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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