Understanding Potential Difference and EMF in Electric Circuits

[tonyjk]

hello... potential difference between two points in a circuit is the work done by the electric field to get a charge from point to another and for the emf it's also the work done but my question is for a potential difference the work is negative( the electrons lose energy) and for the emf the work done is positive( the electrons gain energy) ? or what? and the potential measured between a point of a circuit and the ground is it an emf or a potential difference( so it's like a given energy or a loss of energy)? thank you:D

 

[tonyjk]

i have read some threads made here but i didnt 100% get the response through them so please if any of the admins or members can help me.. thanks again

 

[Yuri B.]

Emf, voltage, electric charge, potential (difference), seems to refer to the more or less the same form of energy. They fade doing work if the energy is not renewed.

 

[tonyjk]

so the emf and potential difference are the same in a circuit? they have the same effects?

 

[dlgoff]

Voltage is electric potential energy per unit charge, measured in joules per coulomb ( = volts). It is often referred to as "electric potential", which then must be distinguished from electric potential energy by noting that the "potential" is a "per-unit-charge" quantity.

The emf represents energy per unit charge (voltage) which has been made available by the generating mechanism and is not a "force".

This is a good explanation. For further reading see. http://hyperphysics.phy-astr.gsu.edu/hbase/electric/volcon.html#c1

 

[tonyjk]

okay i understand but my question is in a circuit when we measure a potential at a point A to the mass is it a potential difference or an EMF( if we take an EMF=5V and a resistance and after the resistance the potential is dropped and we have a new potential for exemple equal to 4.25V after the resistance,this potential referred to the mass is it an emf or a potential difference?)