# Potential Difference between two points

1. Oct 16, 2006

### mb85

more so help with the concept than anything else.

A battery has an EMP of 12v and an internal resistance of 2 ohms. Is the terminal-to-terminal potential difference greater than, less than, or equal to 12v if the current in the battery is from a) from the neg to pos. terminal b) from pos to neg terminal c) zero?

I realize that you loose potential in going from a neg. to pos. terminal.
so for:
a) +E -iR = 0
b) -E + iR = 0
c) they are equal.

im just a little foggy on why b is greater than 12V.

2. Oct 16, 2006

### OlderDan

If E and i are positive, b) should be E + iR and neither a) nor b) should be set = 0. These are the terminal voltages. They are not zero.

In b), something out there (perhaps a higher voltage battery, or a battery charger) is forcing current "backwards" through the battery

Last edited: Oct 16, 2006
3. Oct 16, 2006

### mb85

oh i was doing the loop rule by accident. thats why i was setting them equal to zero.