The physical meaning of electric potential

[bachir1994]

I read that : An electric potential (also called the electric field potential or the electrostatic potential) is the amount of work needed to move a unit positive charge from a reference point to a specific point inside the field without producing any acceleration. Typically, the reference point is Earth or a point at Infinity. I don't inderstand two things :" the reference is from infinity " ? and "without producing acceleration" ? please somewone to help me to understand this.
Thank you all .

 

[Dale]

I don't inderstand two things :" the reference is from infinity " ?

Imagine the reference is 1 light year away, a specific amount of work would be required. Now change the reference to 2 light years away, the field is very weak, so the additional work is very small. Now change to 3 light years away, the additional work is even smaller. This series happens to have a finite limit as the distance goes to infinity, which gives the voltage referenced to infinity.

 

[bachir1994]

thank you for this explanations, so its for this that : the electric potential between two charges Qa and Qb is defined that is the path integral from infinity to B of Qa/(4 π ε0 r)