Physics problems driving me crazy- each book has different formulas

[x86]

Homework Statement

The electric potential difference between two parallel metal plates is delta V. The plates are separated by a distance of 3 .0 mm and the electric field between the plats is E = 250 V / m. Calculate delta V

Homework Equations

E = - delta V / delta D

The Attempt at a Solution

250 V / m = - 120 V / D

D = -0.75 V

The answer says 0.75 V.

Is it positive or negative? can someone help?

The prior question I solved, using this formula and plugging in values gave me -1.2 * 10^3 N/C.

So, why is it positive? Thanks

 

[ehild]

"Electric field between the plates" does not specify the direction of the field. It points to the lower potential. Calculate with the absolute values. A distance is always positive.

ehild