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VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: Studyinghard on December 04, 2009, 07:27:51 pm

Title: Unit 1 Physics q's.
Post by: Studyinghard on December 04, 2009, 07:27:51 pm

Hey guys,

Need some help :P

Electromotive force ()
At one time it was thought that the charges were subjected to some electrical force to make them move – an electromotive force (emf ). We
still use this term, but now understand it in terms of energy available to do work. A battery has an emf, which is then reduced by the internal resistance of the battery. Thus, the potential difference across the terminals of the battery is the emf less the potential difference across the internal resistance. The internal resistance is treated as a series resistance that in most, but not all, cases is very small (negligible) compared to the resistance in the rest of the circuit.

Is there a way to explain this in simple terms :P

Maybe some pics :)

Thanks

Title: Re: Unit 1 Physics q's.
Post by: /0 on December 04, 2009, 09:49:14 pm

The internal resistance is just like any resistor, only it 'lives' inside the battery. The EMF is the voltage created by the battery before some of the voltage is lost to internal resistance.

The voltage across the whole battery is



(http://www.iop.org/activity/education/Projects/Teaching%20Advanced%20Physics/Electricity/Images%20100/img_mid_4092.gif)