How do i find the magnitude potential difference

Find the magnitude difference between two points located 1.4 m apart in a uniform 650 N/C electric field, if a line between the points is parallel to the field.

Potential difference V = integral of the electric field*ds over 1.4m = integral E dot ds over 1.4m. The "dot" refers to the dot-product of E and ds, both of which are vectors. If they're aligned, it's just E*s, s = 1.4m

So, E = 650N/C and s = 1.4m so = 650*1.4 = 910V.