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# Electricity EMF and Internal Resistance question watch

1. (Original post by samb1234)
It works exactly the same for the internal resistance, you can just use a standard power formula. If you don't already know them, it would be worth getting comfortable with using p=I^2 R and p=v^2 /R as they make the written questions much easier
i don't know which values to use
2. (Original post by thefatone)
i don't know which values to use
p=I^2 R (would always use in this situation as it is a series circuit so by definition current is same everywhere, so don't have to do any extra calculations). So basically for the power lost due to internal resistance p=I^2 r where r is internal resistance
3. (Original post by samb1234)
p=I^2 R (would always use in this situation as it is a series circuit so by definition current is same everywhere, so don't have to do any extra calculations). So basically for the power lost due to internal resistance p=I^2 r where r is internal resistance
oh right i used the wrong value of resistance xD
4. (Original post by samb1234)
p=I^2 R (would always use in this situation as it is a series circuit so by definition current is same everywhere, so don't have to do any extra calculations). So basically for the power lost due to internal resistance p=I^2 r where r is internal resistance
pd across terminals of a cell was 1.1v when current is 0.2A and 1.3v when current was 0.1A
how do i find internal resistance of cell and emf?
5. (Original post by thefatone)
pd across terminals of a cell was 1.1v when current is 0.2A and 1.3v when current was 0.1A
how do i find internal resistance of cell and emf?
Vt=emf-ir

solve simultaneously with 2 different currents
6. (Original post by samb1234)
Vt=emf-ir

solve simultaneously with 2 different currents
ok thanks

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