# Tell me how I should manipulate my formulas to answer these electric potential stuff

pokeefer

## Homework Statement

Protons are being accelerated through a potential difference of 5,000 V in the gun of a particle accelerator. They must pass between two parallel deflecting plates that are 0.06 m long and 0.02 m apart with a potential difference between them of 1,500 V

## Homework Equations

Ep = kQ1Q2 / d^2
E= V/d
F = QE
V = Change in Ep / Q
I = Q/t
V = kQ / d

## The Attempt at a Solution

First part asks me:

What is the kinetic energy of protons leaving the gun?

What do i do?

## Answers and Replies

Homework Helper

In all these acceleration-through-potential-difference problems, there are just two approaches. The first has all the details:
potential dif causes E field which causes F on electrons which causes them to accelerate which increases their velocity. You can write a basic formula for each "causes" and combine them in a chain to find any of those quantities given any other.

The second approach is a big shortcut that often finds what you want. Use the definition of potential difference: it is the energy given (or taken) from each charge, V = Energy/Q. Quite often you want the speed of the charge so you replace Energy with the KE formula.

pokeefer

So would I do something like this?

V = Energy Potential / Q

V = Energy Kinetic / Q

5,000 v = Energy Kinetic / (1.6 x 10^-19)

Then to find velocity you do:

Energy Kinetic = 1/2 mv^2

And in the mass you put the mass of the proton (1.67 x 10^-27) ?

Just wanna make sure.

Homework Helper

It all sounds good!