Problem 11-35 Potential and kinematics

A proton is accelerated from rest from a positively charged plate to a parallel negatively charged plate. The separation of the plates is \(8.9\; mm.\) If the potential difference between the plates is \(75.3\; V,\) what is the speed of the proton just as it hits the negative plate?
[Ans. \(1.2 \times 10^5\; m/s\)]

Let's start with a diagram of the situation. Which is correct?

Three possible diagrams of a proton accelerated from a positively charged plate to a negatively charged plate; A, B, C.

(A)

(B)

(C)