Potential difference and current

  • #1
Supernova123
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I have trouble understanding the internal resistance experiment in which potential difference decreases as current increases because I thought they are usually directly proportional to each other. Is there any concept that I am missing? I know that the lost voltage will be greater as current increases but doesn't this apply to other experiments as well? Does the experimental setup have anything to do with it?
 

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  • #2
sophiecentaur
Science Advisor
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I have trouble understanding the internal resistance experiment in which potential difference decreases as current increases because I thought they are usually directly proportional to each other. Is there any concept that I am missing? I know that the lost voltage will be greater as current increases but doesn't this apply to other experiments as well? Does the experimental setup have anything to do with it?
Hi and welcome.
Yes V=IR always. The V in question, however, is the V that is dropped / lost as current goes through the internal resistance - leaving fewer volts, delivered to the battery terminals. The volts lost 'inside' plus the volts across the load (the terminals) will add up to the original battery voltage - or emf, as it's called. The rules apply everywhere and if you draw out the circuit you can see what's happening. Otherwise look at this link.
 
  • #3
Supernova123
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I think I understand now. Thanks for your time :)
 
  • #4
sophiecentaur
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I think I understand now. Thanks for your time :)

Electricity can be confusing as it sometimes seems counter-intuitive. But you can be sure that it always follows the rules and it will not let you down with a 'but not when there's an R in the month' type of exception. The secret is always to work from what you know towards what you don't know. (More difficult to do than you would think in some cases.)
 

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