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# OCR A Module 2 - Kirchoff II Possibly? watch

1. been revising my module 2 for the synoptic exam and i've come across something i... um... didnt appreciate existed in this form. it never came up in my module 2 exam put it that way... anyroad...

V = @ - IR

it looks like (and therefore i presume it is) some kind of manipulative combobulation of Kirchoff's second law.

Voltage = emf[battery] - sum{IR}[of all components in the circuit]

however, i thought kirchoff said emf = sum{IR}. but this says there is a voltage drop. this flummoxed me - the only thing i can think of is that we're using "real" batteries for once and that "emf{battery} - sum{IR}" gives the voltage drop due to the internal resistance of the battery. any clarification on this for me?
2. (Original post by El Chueco)
been revising my module 2 for the synoptic exam and i've come across something i... um... didnt appreciate existed in this form. it never came up in my module 2 exam put it that way... anyroad...

V = @ - IR

it looks like (and therefore i presume it is) some kind of manipulative combobulation of Kirchoff's second law.

Voltage = emf[battery] - sum{IR}[of all components in the circuit]

however, i thought kirchoff said emf = sum{IR}. but this says there is a voltage drop. this flummoxed me - the only thing i can think of is that we're using "real" batteries for once and that "emf{battery} - sum{IR}" gives the voltage drop due to the internal resistance of the battery. any clarification on this for me?
Well as you say it could either be accommodating for the internal resistance, as seems likely, but it could also be a rearrangement of the normal equation with 2 components (other than the battery):
V + IR = @
Being the normal, but if this is a standard equation, I'd go with the internal resistance.
3. (Original post by Golden Maverick)
Well as you say it could either be accommodating for the internal resistance, as seems likely, but it could also be a rearrangement of the normal equation with 2 components (other than the battery):
V + IR = @
Being the normal, but if this is a standard equation, I'd go with the internal resistance.
coolio. cheers Mav!

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