The emf of the battery source can be defined as the potential difference between two electrodes when no current is flowing. Now how I can apply this definition of the emf which is produces by change in the magnetic flux to the coil. Which two points I have to take for defining the emf produce in closed loop. Suppose 2 volt emf is produces in the closed looploop when I change the magnetic flux linked with it. Now in which two points in the loop the potential difference 2volt is created.