Consider two points A and B with small distance dr between them. If q is the change placed at B and move toward A then,
At point B, force on q = qE
At point A,force on q = qE
The potential difference between two points A and B will be
VB-VA- dv = W(AB)lq V(AB)=F.dr.cos 180/q
-ve sign indicates that potential decreases in the direction of electric field.
