I think this is a good question to discuss, so I put it on the
forum
It means a difference in potential.
Suppose we let the potential at P be 24 V, the potential at R will
thus be 0V. This is because the battery is in between, and thus
cause a rise of potential of 24V from R to P (the line on the
right).
Similarly, if we let potential at P be 28V, potential at R will
then be 4V.
Thus, if we talk only about potential, there's not much
significance.
The significance only comes when we talk about the potential
difference, but it represents a difference in potential, no matter
what value we assign P to be.
Ok, that was a bit more in depth. At O levels, you can see
potential difference as the drop in potential across 2 pts. Eg,
from P to Q, what is the voltage drop? To fully understand, you
will need to understand Kirchoff's law, which should be explained
in your textbook...
