The definition for electric field strength

I'm covering electric fields in my book and it says "electric field strength is defined by the equation E = F/Q and not by E = V/d" where Q is charge, F is force, E is electrical field strength, V is potential difference and d is the distance between parallel oppositely charged plates.

Please tell me if the book is correct and if so why it's correct because i would've thought you could define electrical field strength with either equation 🙂

E=F/Q is usually used for a radial, non-uniform field.
E=V/D is usually used for a uniform field such as those found on metal plates with a potential difference across them.


However when we were answering a question on the defintion, I am certain we wrote the unit of force per coulomb charge.
This is what I recall my teacher sayjng.

In an exam question, I think it is always best to state what the equation means.
In both uniform and radial fields, electrical field strength can be defined as the force applied per unit charge. As it happens, $Vm^{-1}$ and $NC^{-1}$ are equivalent units - if you were to write them out in SI units, they'd be the same.