How Do Voltage Arrows Indicate Polarity?

[cytochrome]

I see a lot of voltage drops being represented as an arrow. Say a voltage of 20V is represented as an arrow from point a to point b.

What is the polarity of and b then? Do the arrows to represent voltage usually go from + to - or from - to +?

Thanks for your time.

 

[sunrah]

By convention the arrows represent a positive change in potential so they point to the higher voltage.

 

[cytochrome]

I'm still trying to make sure I really understand this. Can someone answer my example question?

Say a voltage of 20V is represented as an arrow from point a to point b. What is the polarity of a and b then?